Katherine Kaplan

All Publications

• Sleep insufficiency and bedtime irregularity in children with ADHD: A population-based analysis. Sleep medicine Leman, T. Y., Barden, S., Swisher, V. S., Joyce, D. S., Kaplan, K. A., Zeitzer, J. M., Loo, S. K., Ricketts, E. J. 2024; 121: 117-126

  Abstract

  Sleep is impaired in children with attention-deficit/hyperactivity disorder (ADHD). However, population-based examination of indicators of sleep insufficiency and bedtime irregularity is limited. This investigation examined associations between ADHD, weeknight sleep insufficiency, and bedtime irregularity in a nationally-representative child sample, and indicators of these sleep outcomes in ADHD.Parents of children aged 3-17 years with ADHD (n = 7671) were surveyed through the 2020-2021 National Survey of Children's Health. Inverse probability of treatment weighting generated a weighted matched control sample (n = 51,572). Weighted generalized linear models were performed without and with age-stratification to examine associations between ADHD and sleep, adjusting for sociodemographics in the full sample, and between nineteen sociodemographic and clinical variables and sleep in ADHD.Having ADHD was associated with increased odds of sleep insufficiency and bedtime irregularity relative to controls, even after adjusting for sociodemographic variables. In ADHD, older age was associated with lower sleep insufficiency and greater bedtime irregularity. Black race, increased poverty, higher ADHD severity, depression, and increased screen time were associated with greater sleep insufficiency and bedtime irregularity. Adverse childhood experiences (ACEs) were associated with greater sleep insufficiency. Behavioral/conduct problems, female sex, and absence of both ADHD medication use and ASD diagnosis were associated with poorer bedtime irregularity. Age-stratified results are reported in text.Children with ADHD face heightened risk for insufficient sleep and irregular bedtimes. Findings suggest intervention targets (e.g., Black race, poverty, depression, screen time) to improve both sleep insufficiency and bedtime irregularity. Results highlight ACEs and behavioral/conduct problems as targets to improve sleep insufficiency and bedtime regularity, respectively. Age-stratified findings are discussed.

  View details for DOI 10.1016/j.sleep.2024.06.015

  View details for PubMedID 38959718

• A MACHINE LEARNING APPROACH TO IDENTIFY FACTORS ASSOCIATED WITH ADOLESCENT SLEEP OUTCOMES Ricketts, E., Kaplan, K., McMakin, D., Patriarca, G., Mathew, G., McGrew, T., Chang, A., Hale, L. OXFORD UNIV PRESS INC. 2024

  View details for Web of Science ID 001262172001338

• Recent advances in sleep and depression. Current opinion in psychiatry Mirchandaney, R., Asarnow, L. D., Kaplan, K. A. 2023; 36 (1): 34-40

  Abstract

  There is increasing interest in the connection between sleep disturbances and mood disorders. The purpose of this review is to summarize and evaluate current research on the role of sleep disturbance in the development of depression, as well as to describe recent advances in treatments that improve both sleep and depression symptoms.Relevant publications included in this review cover a wide range of topics related to sleep and depression. Data from large longitudinal studies suggest that insomnia and evening circadian preference are unique risk factors for depression. Depression treatment studies indicate poorer outcomes for those with comorbid sleep disturbances. A few recent trials of cognitive behavioral therapy for insomnia and triple chronotherapy in unipolar depression have shown promising results.Sleep disturbance is a modifiable risk factor in the development and maintenance of depression. In the context of current depression, although the data is mixed, some evidence suggests treating sleep disturbance can improve overall outcomes. Recent evidence also suggests that treating sleep disturbance may prevent the future depressive episodes.

  View details for DOI 10.1097/YCO.0000000000000837

  View details for PubMedID 36449730

• N2 AND WAKEFULNESS DRIVE SUBJECTIVE SLEEP SATISFACTION IN ADULTS Lok, R., Chawra, D., Hon, F., Ha, M., Kaplan, K., Zeitzer, J. OXFORD UNIV PRESS INC. 2022: A99

  View details for Web of Science ID 000838094800218

• Objective underpinnings of self-reported sleep quality in middle-aged and older adults: the importance of N2 and wakefulness. Biological psychology Lok, R., Chawra, D., Hon, F., Ha, M., Kaplan, K. A., Zeitzer, J. M. 2022: 108290

  Abstract

  STUDY OBJECTIVES: The measurable aspects of brain function (polysomnography, PSG) that are correlated with sleep satisfaction are poorly understood. Using recent developments in automated sleep scoring, which remove the within- and between-rater error associated with human scoring, we examine whether PSG measures are associated with sleep satisfaction.DESIGN AND SETTING: A single night of PSG data was compared to contemporaneously collected measures of sleep satisfaction with Random Forest regressions. Whole and partial night PSG data were scored using a novel machine learning algorithm.PARTICIPANTS: Community-dwelling adults (N=3,165) who participated in the Sleep Heart Health Study.INTERVENTIONS: None MEASUREMENTS AND RESULTS: Models explained 30% of sleep depth and 27% of sleep restfulness, with a similar top four predictors: minutes of N2 sleep, sleep efficiency, age, and minutes of wake after sleep onset (WASO). With increasing self-reported sleep quality, there was a progressive increase in N2 and decrease in WASO of similar magnitude, without systematic changes in N1, N3 or REM sleep. In comparing those with the best and worst self-reported sleep satisfaction, there was a range of approximately 30minutes more N2, 30minutes less WASO, an improvement of sleep efficiency of 7-8%, and an age span of 3-5 years. Examination of sleep most proximal to morning awakening revealed no greater explanatory power than the whole-night data set.CONCLUSIONS: Higher N2 and concomitant lower wake is associated with improved sleep satisfaction. Interventions that specifically target these may be suitable for improving the self-reported sleep experience.

  View details for DOI 10.1016/j.biopsycho.2022.108290

  View details for PubMedID 35192907

• The Hypersomnia Severity Index: reliability, construct and criterion validity in a clinical sample with sleep disorders. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine Fernandez-Mendoza, J., Puzino, K., Amatrudo, G., Bourchtein, E., Calhoun, S. L., Plante, D. T., Kaplan, K. 2021

  Abstract

  STUDY OBJECTIVES: The Hypersomnia Severity Index (HSI) was designed to assess severity and impairment of hypersomnolence and validated in persons with psychiatric disorders. Little is known about its psychometric properties in clinical samples with sleep disorders.METHODS: 158 patients (44.1±16.4 years old, 29.1% male, 19.6% racial/ethnic minority) evaluated at the Behavioral Sleep Medicine program of Penn State Health Sleep Research & Treatment Center completed the HSI and other patient-reported outcomes. We examined the HSI's reliability and factorial, construct and criterion validity.RESULTS: The HSI showed satisfactory internal consistency (alpha=0.79). A two-factor structure, reflecting symptoms (HSI-S) and impairment (HSI-I), explained 56.2% of the variance. Convergent validity with Epworth Sleepiness Scale (ESS) was optimal (r=0.65) but greater for HSI-S (r=0.69) than HSI-I (r=0.39). Divergent validity was optimal for HSI-S against unrelated measures of sleep effort, reactivity and incompatible behaviors (r≤0.02). Construct validity showed higher scores in subjects with central disorders of hypersomnolence (CDH) and lower scores in subjects with chronic insomnia disorder (CID) compared to those with other sleep disorders; however, these divergent scores were primarily driven by the HSI-S rather than the HSI-I. Criterion validity showed that a HSI-S cut-off score ≥8 provided the best balance in sensitivity/specificity (0.82/0.78) to identify CDH (AUC=0.85).CONCLUSIONS: The HSI shows satisfactory indices of reliability and validity in a clinical sample. Its construct and criterion validity are supported by its divergent association with other patient-reported outcomes and CDH vs. CID diagnoses as well as the adequate sensitivity/specificity of its HSI-S cut-off score to reliably identify CDH.

  View details for DOI 10.5664/jcsm.9426

  View details for PubMedID 34032202

• Sleep and sleep treatments in bipolar disorder. Current opinion in psychology Kaplan, K. A. 2020; 34: 117–22

  Abstract

  Sleep and circadian disturbances in bipolar disorder are common and persistent within and between illness episodes. Insomnia, hypersomnia, reduced need for sleep, sleep schedule variability and circadian rhythm disorders are frequently observed. In this article, recent research is reviewed suggesting that the presence of sleep disturbance is associated with functional impairment, interacts with other physical and environmental systems (e.g. physical activity, light exposure), and may attenuate response to treatment. Established and emerging treatments for various sleep disturbances are reviewed, with emphasis on applications for light therapy and adapted cognitive behavioral therapy. There remains a critical need to understand the co-occurrence of various sleep disturbances, develop, and refine treatment approaches (especially for hypersomnia/long sleep duration) and adapt wearable and smartphone technologies to aid assessment and intervention.

  View details for DOI 10.1016/j.copsyc.2020.02.001

  View details for PubMedID 32203912

• Subjective sleep quality is poorly associated with actigraphy and heart rate measures in community-dwelling older men. Sleep medicine Faerman, A. n., Kaplan, K. A., Zeitzer, J. M. 2020; 73: 154–61

  Abstract

  There has been a proliferation in the use of commercially-available accelerometry- and heart rate-based wearable devices to monitor sleep. While the underlying technology is reasonable at detecting sleep quantity, the ability of these devices to predict subjective sleep quality is currently unknown. We tested whether the fundamental signals from such devices are useful in determining subjective sleep quality.Older, community-dwelling men (76.5 ± 5.77 years) enrolled in the Osteoporotic Fractures in Men Study (MrOS) participated in an overnight sleep study during which sleep was monitored with actigraphy (wrist-worn accelerometry) and polysomnography (PSG), including electrocardiography (N = 1141). Subjective sleep quality was determined the next morning using 5-point Likert-type scales of sleep depth and restfulness. Lasso and random forest regression models analyzed the relationship between actigraph-determined sleep variables, the shape of the activity patterns during sleep (functional principal component analysis), average heart rate, heart rate variability (HRV), demographics, and self-reported depression, anxiety, habitual sleep, and daytime sleepiness measures.Actigraphy data, in combination with heart rate, HRV, demographic, and psychological variables, do not predict well subjective sleep quality (R2 = 0.025 to 0.162).Findings are consistent with previous studies that objective sleep measures are not well correlated with subjective sleep quality. Developing validated biomarkers of subjective sleep quality could improve both existing and novel treatment modalities and advance sleep medicine towards precision healthcare standards.

  View details for DOI 10.1016/j.sleep.2020.04.012

  View details for PubMedID 32836083

• A comparison of sleep, depressive symptoms, and parental perceptions between U.S. and Taiwan adolescents with self-reported sleep problems. Sleep advances : a journal of the Sleep Research Society Yang, Y., Kaplan, K. A., Zeitzer, J. M. 2020; 1 (1): zpaa004

  Abstract

  Study Objectives: Inadequate sleep is pervasive among teens worldwide, resulting in daytime sleepiness and, in some cases, depressive symptoms. In addition to their own behavioral choices, parent perceptions may also play a role in adolescent sleep. This study conducted a preliminary evaluation of the antecedents and consequences of sleep factors among adolescents in the United States and Taiwan.Methods: Participants were adolescents with self-reported sleep concerns from academically similar schools in Taiwan (n = 548) and northern California, United States (n = 128). Questionnaires on sleep and mood were administered to both the teens and parents.Results: While Taiwanese students' self-reported sleep behavior was generally better than U.S. students (p < .01), Taiwanese students had higher overall self-reported sleepiness (p < .01). Furthermore, Taiwanese parents reported teen sleep durations of 6.53 ± .827 hours per night during the week (with 45% perceiving this as sufficient), while U.S. parents reported teen sleep durations of 7.22 ± .930 hours (with 27% perceiving this as sufficient). Adolescents in both cohorts had high levels of symptoms consistent with depression (Taiwan: 70%, United States: 62%), which was associated with shorter sleep times for both cohorts and evening chronotype in the Taiwanese, but not U.S., adolescents.Conclusions: Some differences exist between Taiwanese and U.S. adolescents, with generally better sleep and less sleepiness reported among students in the United States, and Taiwanese students' sleep influenced more strongly by chronotype. Furthermore, Taiwanese parents reported less concern about their child's insufficient sleep, despite the fact that inadequate sleep is strongly associated with depressive symptoms for both cohorts.

  View details for DOI 10.1093/sleepadvances/zpaa004

  View details for PubMedID 33345187

• Effect of Light Flashes vs Sham Therapy During Sleep With Adjunct Cognitive Behavioral Therapy on Sleep Quality Among Adolescents: A Randomized Clinical Trial. JAMA network open Kaplan, K. A., Mashash, M., Williams, R., Batchelder, H., Starr-Glass, L., Zeitzer, J. M. 2019; 2 (9): e1911944

  Abstract

  Importance: Owing to biological, behavioral, and societal factors, sleep duration in teenagers is often severely truncated, leading to pervasive sleep deprivation.Objective: To determine whether a novel intervention, using both light exposure during sleep and cognitive behavioral therapy (CBT), would increase total sleep time in teenagers by enabling them to go to sleep earlier than usual.Design, Setting, and Participants: This double-blind, placebo-controlled, randomized clinical trial, conducted between November 1, 2013, and May 31, 2016, among 102 adolescents enrolled full-time in grades 9 to 12, who expressed difficulty going to bed earlier and waking up early enough, was composed of 2 phases. In phase 1, participants were assigned to receive either 3 weeks of light or sham therapy and were asked to try to go to sleep earlier. In phase 2, participants received 4 brief CBT sessions in addition to a modified light or sham therapy. All analyses were performed on an intent-to-treat basis.Interventions: Light therapy consisted of receiving a 3-millisecond light flash every 20 seconds during the final 3 hours of sleep (phase 1) or final 2 hours of sleep (phase 2). Sham therapy used an identical device, but delivered 1 minute of light pulses (appearing in 20-second intervals, for a total of 3 pulses) per hour during the final 3 hours of sleep (phase 1) or 2 hours of sleep (phase 2). Light therapy occurred every night during the 4-week intervention. Cognitive behavioral therapy consisted of four 50-minute in-person sessions once per week.Main Outcomes and Measures: Primary outcome measures included diary-based sleep times, momentary ratings of evening sleepiness, and subjective measures of sleepiness and sleep quality.Results: Among the 102 participants (54 female [52.9%]; mean [SD] age, 15.6 [1.1] years), 72 were enrolled in phase 1 and 30 were enrolled in phase 2. Mixed-effects models revealed that light therapy alone was inadequate in changing the timing of sleep. However, compared with sham therapy plus CBT alone, light therapy plus CBT significantly moved sleep onset a mean (SD) of 50.1 (27.5) minutes earlier and increased nightly total sleep time by a mean (SD) of 43.3 (35.0) minutes. Light therapy plus CBT also resulted in a 7-fold greater increase in bedtime compliance than that observed among participants receiving sham plus CBT (mean [SD], 2.21 [3.91] vs 0.29 [0.76]), as well as a mean 0.55-point increase in subjective evening sleepiness as compared with a mean 0.48-point decrease in participants receiving sham plus CBT as measured on a 7-point sleepiness scale.Conclusions and Relevance: This study found that light exposure during sleep, in combination with a brief, motivation-focused CBT intervention, was able to consistently move bedtimes earlier and increase total sleep time in teenagers. This type of passive light intervention in teenagers may lead to novel therapeutic applications.Trial Registration: ClinicalTrials.gov identifier: NCT01406691.

  View details for DOI 10.1001/jamanetworkopen.2019.11944

  View details for PubMedID 31553469

• Development and validation of the Hypersomnia Severity Index (HSI): A measure to assess hypersomnia severity and impairment in psychiatric disorders. Psychiatry research Kaplan, K. A., Plante, D. T., Cook, J. D., Harvey, A. G. 2019; 281: 112547

  Abstract

  Hypersomnia is common in psychiatric disorders, yet there are few self-report measures that adequately characterize this sleep disturbance. The objective of this study was to validate the Hypersomnia Severity Index (HSI), a tool designed to measure severity, distress and impairment of hypersomnia in psychiatric populations. Psychometric properties were evaluated in an undergraduate Scale Development sample (N = 381) and two psychiatric Scale Validation samples: euthymic bipolar participants with a range of sleep complaints (N = 89), and unmedicated unipolar depressed participants (N = 21) meeting operational criteria for hypersomnolence disorder. Exploratory factor analysis and confirmatory factor analysis in the Scale Development and Validation samples, respectively, suggested a two-factor structure representing Hypersomnia Symptoms and Distress/Impairment best fit the data. Convergent validity was established by significant associations with the Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and the Sheehan Disability Scale in both samples. Construct validity was further supported by significant correlations between the Scale Validation sample and two weeks of diary- and actigraphy-determined total sleep time and time in bed. A cutoff score of 10 maximally discriminated between those with hypersomnia and those without. The HSI shows promise as a measure of hypersomnia that is commonly seen in psychiatric disorders, and may be of use to both researchers and clinicians. SUPPORT: This work is supported by grants from the American Sleep Medicine Foundation (76-JF-12), the Brain and Behavior Research Foundation (19193), and NIMHK23MH099234 (DTP); National Science Foundation Graduate Research Fellowship Program and Stanford Child Health Research Institute (KAK); and R34MH080958 and R01MH105513 (AGH).

  View details for DOI 10.1016/j.psychres.2019.112547

  View details for PubMedID 31494450

• Rise and shine: A treatment experiment testing a morning routine to decrease subjective sleep inertia in insomnia and bipolar disorder. Behaviour research and therapy Kaplan, K. A., Talavera, D. C., Harvey, A. G. 2018; 111: 106–12

  Abstract

  Sleep inertia involves decreased performance or disorientation upon waking that lasts several hours and impairs functioning. Though sleep inertia is common in insomnia and may interfere with treatment, Cognitive Behavioral Therapy for Insomnia (CBTI) does not routinely include a component to address sleep inertia. The present study evaluates such a component, the RISE-UP routine, in CBTI for insomnia comorbid with bipolar disorder. We hypothesized that the RISE-UP routine would increase physical activity in the morning and reduce the duration and severity of self-reported sleep inertia. Sleep and sleep inertia were monitored in the week prior to and following the intervention with daily sleep diaries, actigraphy, and ecological momentary assessment (EMA). Participants were randomized to a bipolar-specific modification of CBT-I (CBTI-BP) with RISE-UP (N = 20) or a psychoeducation (PE) comparison condition (N = 20). The treatment experiment (RISE-UP vs PE) was completed in the first treatment session. RISE-UP reduced the duration and severity of self-reported sleep inertia, as measured by diary reports and by EMA ratings, and was rated as acceptable and credible. Compliance was high, and increases in morning activity levels were verified via actigraphy. Addressing morning sleep inertia via behavioral modifications upon waking may be a useful addition to CBTI.

  View details for PubMedID 30399503

• DAYTIME INSOMNIA SYMPTOMS NEGATIVELY PREDICT ANHEDONIA IN PATIENTS WITH COMORBID MAJOR DEPRESSIVE DISORDER AND INSOMNIA DISORDER Osorno, R. A., Kaplan, K., Krystal, A., Buysse, D., Edinger, J., Manber, R. OXFORD UNIV PRESS INC. 2018: A361–A362

  View details for Web of Science ID 000431183401179

• You'll feel better in the morning: slow wave activity and overnight mood regulation in interepisode bipolar disorder PSYCHOLOGICAL MEDICINE Soehner, A. M., Kaplan, K. A., Saletin, J. M., Talbot, L. S., Hairston, I. S., Gruber, J., Eidelman, P., Walker, M. P., Harvey, A. G. 2018; 48 (2): 249–60

  Abstract

  Sleep disturbances are prominent correlates of acute mood episodes and inadequate recovery in bipolar disorder (BD), yet the mechanistic relationship between sleep physiology and mood remains poorly understood. Using a series of pre-sleep mood inductions and overnight sleep recording, this study examined the relationship between overnight mood regulation and a marker of sleep intensity (non-rapid eye movement sleep slow wave activity; NREM SWA) during the interepisode phase of BD.Adults with interepisode BD type 1 (BD; n = 20) and healthy adult controls (CTL; n = 23) slept in the laboratory for a screening night, a neutral mood induction night (baseline), a happy mood induction night, and a sad mood induction night. NREM SWA (0.75-4.75 Hz) was derived from overnight sleep EEG recordings. Overnight mood regulation was evaluated using an affect grid pleasantness rating post-mood induction (pre-sleep) and the next morning.Overnight mood regulation did not differ between groups following the sad or happy inductions. SWA did not significantly change for either group on the sad induction night compared with baseline. In BD only, SWA on the sad night was related to impaired overnight negative mood regulation. On the happy induction night, SWA increased relative to baseline in both groups, though SWA was not related to overnight mood regulation for either group.These findings indicate that SWA disruption may play a role in sustaining negative mood state from the previous night in interepisode BD. However, positive mood state could enhance SWA in bipolar patients and healthy adults.

  View details for PubMedID 28625231

  View details for PubMedCentralID PMC5736461

• Correlates of sleep quality in midlife and beyond: a machine learning analysis. Sleep medicine Kaplan, K. A., Hardas, P. P., Redline, S., Zeitzer, J. M. 2017; 34: 162-167

  Abstract

  In older adults, traditional metrics derived from polysomnography (PSG) are not well correlated with subjective sleep quality. Little is known about whether the association between PSG and subjective sleep quality changes with age, or whether quantitative electroencephalography (qEEG) is associated with sleep quality. Therefore, we examined the relationship between subjective sleep quality and objective sleep characteristics (standard PSG and qEEG) across middle to older adulthood.Using cross-sectional analyses of 3173 community-dwelling men and women aged between 39 and 90 participating in the Sleep Heart Health Study, we examined the relationship between a morning rating of the prior night's sleep quality (sleep depth and restfulness) and polysomnographic, and qEEG descriptors of that single night of sleep, along with clinical and demographic measures. Multivariable models were constructed using two machine learning methods, namely lasso penalized regressions and random forests.Little variance was explained across models. Greater objective sleep efficiency, reduced wake after sleep onset, and fewer sleep-to-wake stage transitions were each associated with higher sleep quality; qEEG variables contributed little explanatory power. The oldest adults reported the highest sleep quality even as objective sleep deteriorated such that they would rate their sleep better, given the same level of sleep efficiency. Despite this, there were no major differences in the predictors of subjective sleep across the age span.Standard metrics derived from PSG, including qEEG, contribute little to explaining subjective sleep quality in middle-aged to older adults. The objective correlates of subjective sleep quality do not appear to systematically change with age despite a change in the relationship between subjective sleep quality and objective sleep efficiency.

  View details for DOI 10.1016/j.sleep.2017.03.004

  View details for PubMedID 28522086

• Hypersomnia: an overlooked, but not overestimated, sleep disturbance in bipolar disorder. Evidence-based mental health Kaplan, K. A., Williams, R. 2017

  View details for DOI 10.1136/eb-2016-102433

  View details for PubMedID 28235881

• When a gold standard isn't so golden: Lack of prediction of subjective sleep quality from sleep polysomnography. Biological psychology Kaplan, K. A., Hirshman, J., Hernandez, B., Stefanick, M. L., Hoffman, A. R., Redline, S., Ancoli-Israel, S., Stone, K., Friedman, L., Zeitzer, J. M. 2017; 123: 37-46

  Abstract

  Reports of subjective sleep quality are frequently collected in research and clinical practice. It is unclear, however, how well polysomnographic measures of sleep correlate with subjective reports of prior-night sleep quality in elderly men and women. Furthermore, the relative importance of various polysomnographic, demographic and clinical characteristics in predicting subjective sleep quality is not known. We sought to determine the correlates of subjective sleep quality in older adults using more recently developed machine learning algorithms that are suitable for selecting and ranking important variables.Community-dwelling older men (n=1024) and women (n=459), a subset of those participating in the Osteoporotic Fractures in Men study and the Study of Osteoporotic Fractures study, respectively, completed a single night of at-home polysomnographic recording of sleep followed by a set of morning questions concerning the prior night's sleep quality. Questionnaires concerning demographics and psychological characteristics were also collected prior to the overnight recording and entered into multivariable models. Two machine learning algorithms, lasso penalized regression and random forests, determined variable selection and the ordering of variable importance separately for men and women.Thirty-eight sleep, demographic and clinical correlates of sleep quality were considered. Together, these multivariable models explained only 11-17% of the variance in predicting subjective sleep quality. Objective sleep efficiency emerged as the strongest correlate of subjective sleep quality across all models, and across both sexes. Greater total sleep time and sleep stage transitions were also significant objective correlates of subjective sleep quality. The amount of slow wave sleep obtained was not determined to be important.Overall, the commonly obtained measures of polysomnographically-defined sleep contributed little to subjective ratings of prior-night sleep quality. Though they explained relatively little of the variance, sleep efficiency, total sleep time and sleep stage transitions were among the most important objective correlates.

  View details for DOI 10.1016/j.biopsycho.2016.11.010

  View details for PubMedID 27889439

  View details for PubMedCentralID PMC5292065

• Aberrant nocturnal cortisol and disease progression in women with breast cancer BREAST CANCER RESEARCH AND TREATMENT Zeitzer, J. M., Nouriani, B., Rissling, M. B., Sledge, G. W., Kaplan, K. A., Aasly, L., Palesh, O., Jo, B., Neri, E., Dhabhar, F. S., Spiegel, D. 2016; 158 (1): 43-50

  Abstract

  While a relationship between disruption of circadian rhythms and the progression of cancer has been hypothesized in field and epidemiologic studies, it has never been unequivocally demonstrated. We determined the circadian rhythm of cortisol and sleep in women with advanced breast cancer (ABC) under the conditions necessary to allow for the precise measurement of these variables. Women with ABC (n = 97) and age-matched controls (n = 24) took part in a 24-h intensive physiological monitoring study involving polysomnographic sleep measures and high-density plasma sampling. Sleep was scored using both standard clinical metrics and power spectral analysis. Three-harmonic regression analysis and functional data analysis were used to assess the 24-h and sleep-associated patterns of plasma cortisol, respectively. The circadian pattern of plasma cortisol as described by its timing, timing relative to sleep, or amplitude was indistinguishable between women with ABC and age-matched controls (p's > 0.11, t-tests). There was, however, an aberrant spike of cortisol during the sleep of a subset of women, during which there was an eightfold increase in the amount of objectively measured wake time (p < 0.004, Wilcoxon Signed-Rank). This cortisol aberration was associated with cancer progression such that the larger the aberration, the shorter the disease-free interval (time from initial diagnosis to metastasis; r = -0.30, p = 0.004; linear regression). The same aberrant spike was present in a similar percent of women without ABC and associated with concomitant sleep disruption. A greater understanding of this sleep-related cortisol abnormality, possibly a vulnerability trait, is likely important in our understanding of individual variation in the progression of cancer.

  View details for DOI 10.1007/s10549-016-3864-2

  View details for Web of Science ID 000379494200005

  View details for PubMedID 27314577

  View details for PubMedCentralID PMC4938753

• Treating Insomnia Improves Mood State, Sleep, and Functioning in Bipolar Disorder: A Pilot Randomized Controlled Trial JOURNAL OF CONSULTING AND CLINICAL PSYCHOLOGY Harvey, A. G., Soehner, A. M., Kaplan, K. A., Hein, K., Lee, J., Kanady, J., Li, D., Rabe-Hesketh, S., Ketter, T. A., Neylan, T. C., Buysse, D. J. 2015; 83 (3): 564-577

  Abstract

  To determine if a treatment for interepisode bipolar disorder I patients with insomnia improves mood state, sleep, and functioning.Alongside psychiatric care, interepisode bipolar disorder I participants with insomnia were randomly allocated to a bipolar disorder-specific modification of cognitive behavior therapy for insomnia (CBTI-BP; n = 30) or psychoeducation (PE; n = 28) as a comparison condition. Outcomes were assessed at baseline, the end of 8 sessions of treatment, and 6 months later. This pilot was conducted to determine initial feasibility and generate effect size estimates.During the 6-month follow-up, the CBTI-BP group had fewer days in a bipolar episode relative to the PE group (3.3 days vs. 25.5 days). The CBTI-BP group also experienced a significantly lower hypomania/mania relapse rate (4.6% vs. 31.6%) and a marginally lower overall mood episode relapse rate (13.6% vs. 42.1%) compared with the PE group. Relative to PE, CBTI-BP reduced insomnia severity and led to higher rates of insomnia remission at posttreatment and marginally higher rates at 6 months. Both CBTI-BP and PE showed statistically significant improvement on selected sleep and functional impairment measures. The effects of treatment were well sustained through follow-up for most outcomes, although some decline on secondary sleep benefits was observed.CBTI-BP was associated with reduced risk of mood episode relapse and improved sleep and functioning on certain outcomes in bipolar disorder. Hence, sleep disturbance appears to be an important pathway contributing to bipolar disorder. The need to develop bipolar disorder-specific sleep diary scoring standards is highlighted.

  View details for DOI 10.1037/a0038655

  View details for PubMedID 25622197

• Hypersomnia subtypes, sleep and relapse in bipolar disorder PSYCHOLOGICAL MEDICINE Kaplan, K. A., McGlinchey, E. L., Soehner, A., Gershon, A., TALBOT, L. S., Eidelman, P., Gruber, J., Harvey, A. G. 2015; 45 (8): 1751-1763

  Abstract

  Though poorly defined, hypersomnia is associated with negative health outcomes and new-onset and recurrence of psychiatric illness. Lack of definition impedes generalizability across studies. The present research clarifies hypersomnia diagnoses in bipolar disorder by exploring possible subgroups and their relationship to prospective sleep data and relapse into mood episodes.A community sample of 159 adults (aged 18-70 years) with bipolar spectrum diagnoses, euthymic at study entry, was included. Self-report inventories and clinician-administered interviews determined features of hypersomnia. Participants completed sleep diaries and wore wrist actigraphs at home to obtain prospective sleep data. Approximately 7 months later, psychiatric status was reassessed. Factor analysis and latent profile analysis explored empirical groupings within hypersomnia diagnoses.Factor analyses confirmed two separate subtypes of hypersomnia ('long sleep' and 'excessive sleepiness') that were uncorrelated. Latent profile analyses suggested a four-class solution, with 'long sleep' and 'excessive sleepiness' again representing two separate classes. Prospective sleep data suggested that the sleep of 'long sleepers' is characterized by a long time in bed, not long sleep duration. Longitudinal assessment suggested that 'excessive sleepiness' at baseline predicted mania/hypomania relapse.This study is the largest of hypersomnia to include objective sleep measurement, and refines our understanding of classification, characterization and associated morbidity. Hypersomnia appears to be comprised of two separate subgroups: long sleep and excessive sleepiness. Long sleep is characterized primarily by long bedrest duration. Excessive sleepiness is not associated with longer sleep or bedrest, but predicts relapse to mania/hypomania. Understanding these entities has important research and treatment implications.

  View details for DOI 10.1017/S0033291714002918

  View details for PubMedID 25515854

• Interventions for Sleep Disturbance in Bipolar Disorder. Sleep medicine clinics Harvey, A. G., Kaplan, K. A., Soehner, A. M. 2015; 10 (1): 101-105

  Abstract

  Bipolar disorder is a severe and chronic disorder, ranked in the top 10 leading causes of disability worldwide. Sleep disturbances are strongly coupled with interepisode dysfunction and symptom worsening in bipolar disorder. Experimental studies suggest that sleep deprivation can trigger manic relapse. There is evidence that sleep deprivation can have an adverse impact on emotion regulation the following day. The clinical management of the sleep disturbances experienced by bipolar patients, including insomnia, hypersomnia delayed sleep phase, and irregular sleep-wake schedule, may include medication approaches, psychological interventions, light therapies and sleep deprivation.

  View details for PubMedID 25750600

  View details for PubMedCentralID PMC4347516

• Behavioral Treatment of Insomnia in Early Recovery JOURNAL OF ADDICTION MEDICINE Kaplan, K. A., McQuaid, J., Batki, S. L., Rosenlicht, N. 2014; 8 (6): 395-398

  View details for DOI 10.1097/ADM.0000000000000058

  View details for Web of Science ID 000345117200002

  View details for PubMedID 25369939

• An Evidence-Based Review of Insomnia Treatment in Early Recovery JOURNAL OF ADDICTION MEDICINE Kaplan, K. A., McQuaid, J., Primich, C., Rosenlicht, N. 2014; 8 (6): 389-394

  Abstract

  Accruing evidence indicates that insomnia is prevalent and persistent in early recovery from substance use disorders and may predict relapse. As such, insomnia treatment after abstinence represents an important area for intervention. This article reviews the literature on insomnia predicting new-onset alcohol and substance use disorders, along with evidence for insomnia predicting relapse in recovering populations. Pharmacological and psychological treatment options are presented, and cognitive-behavioral therapy for insomnia applied to recovering populations is described in detail.

  View details for DOI 10.1097/ADM.0000000000000052

  View details for Web of Science ID 000345117200001

  View details for PubMedID 25369938

• Prevalence and clinical correlates of co-occurring insomnia and hypersomnia symptoms in depression JOURNAL OF AFFECTIVE DISORDERS Soehner, A. M., Kaplan, K. A., Harvey, A. G. 2014; 167: 93-97

  Abstract

  The aim was to examine the prevalence and consequences of co-occurring insomnia and hypersomnia symptoms in depressed adults drawn from a representative sample of the U.S. population.Data from 687 National Comorbidity Survey Replication (NCS-R) respondents meeting criteria for a major depressive episode (MDE) in the past year were included. Respondents completed clinical interviews that assessed 12-month DSM-IV disorders, impairment, mental health treatment, and depressive symptom severity. Outcomes were compared between respondents who experienced insomnia symptoms-only (N=404), hypersomnia symptoms-only (N=44), both insomnia and hypersomnia symptoms (N=184) and no sleep problems (N=55) during an MDE.Insomnia and hypersomnia symptoms co-occurred in 27.7% of respondents with past-year MDEs, most frequently in bipolar spectrum disorders and major depressive disorder with dysthymia. Similar to the insomnia-only group, respondents with co-occurring sleep disturbances had more severe depression, and higher rates of past-year impulse control disorders and suicide planning. Similar to the hypersomnia-only group, respondents with co-occurring sleep disturbances had higher rates of past-year drug use disorders and suicide attempts. Compared to the insomnia-only and no sleep problem groups, respondents with both sleep disturbances were more frequently in mental health treatment, seeing a general practitioner, and taking antidepressants.The NCS-R is cross-sectional and did not evaluate sleep disorder diagnoses.Co-occurring insomnia and hypersomnia symptoms were associated with a more severe MDE. Further research is warranted to more fully understand the joint presentation of insomnia and hypersomnia in depression.

  View details for DOI 10.1016/j.jad.2014.05.060

  View details for Web of Science ID 000341335700015

  View details for PubMedID 24953480

  View details for PubMedCentralID PMC4291280

• Physical activity and sleep: Day-to-day associations among individuals with and without bipolar disorder MENTAL HEALTH AND PHYSICAL ACTIVITY McGlinchey, E. L., Gershon, A., Eidelman, P., Kaplan, K. A., Harvey, A. G. 2014; 7 (3): 183-190

  Abstract

  To evaluate the relative role of psychopathology in the relationship between physical activity and sleep, the present study investigated the day-to-day relationship between physical activity and sleep in individuals without a psychiatric disorder and individuals with bipolar disorder using a longitudinal, naturalistic design.Participants in two groups-a healthy group with no psychiatric illness (N=36) and an inter-episode bipolar disorder group (N=32)- were studied over a two-month period. Physical health was assessed by the SF-36. Daily subjective and objective measures of physical activity and sleep were collected. A total of 6,670 physical activity measurements and 6,548 sleep measurements were logged.The bipolar disorder group exhibited poorer physical health on the SF-36 and more sleep disturbance relative to the healthy group. No group differences were found in physical activity, nor in models examining the relationship between physical activity and sleep. Hierarchical linear models indicated that for every standard deviation increase in sleep disturbance (i.e., increased total wake time), there was a three percent decrease in subsequent day physical activity, in both the healthy and bipolar groups. Increased physical activity was associated with improved sleep for participants who reported greater average sleep disturbance.The results for all participants in the study suggest that reduced physical activity and sleep difficulties may be mutually maintaining processes, particularly for individuals who suffer from poor sleep. Findings also raise the potential importance of targeting physical activity and sleep concurrently in interventions aimed at improving physical and mental health.

  View details for DOI 10.1016/j.mhpa.2014.05.003

  View details for Web of Science ID 000348615000010

  View details for PubMedCentralID PMC4260416

• Physical activity and sleep: Day-to-day associations among individuals with and without Bipolar Disorder. Mental health and physical activity McGlinchey, E. L., Gershon, A., Eidelman, P., Kaplan, K. A., Harvey, A. G. 2014; 7 (3): 183-190

  Abstract

  To evaluate the relative role of psychopathology in the relationship between physical activity and sleep, the present study investigated the day-to-day relationship between physical activity and sleep in individuals without a psychiatric disorder and individuals with bipolar disorder using a longitudinal, naturalistic design.Participants in two groups-a healthy group with no psychiatric illness (N=36) and an inter-episode bipolar disorder group (N=32)- were studied over a two-month period. Physical health was assessed by the SF-36. Daily subjective and objective measures of physical activity and sleep were collected. A total of 6,670 physical activity measurements and 6,548 sleep measurements were logged.The bipolar disorder group exhibited poorer physical health on the SF-36 and more sleep disturbance relative to the healthy group. No group differences were found in physical activity, nor in models examining the relationship between physical activity and sleep. Hierarchical linear models indicated that for every standard deviation increase in sleep disturbance (i.e., increased total wake time), there was a three percent decrease in subsequent day physical activity, in both the healthy and bipolar groups. Increased physical activity was associated with improved sleep for participants who reported greater average sleep disturbance.The results for all participants in the study suggest that reduced physical activity and sleep difficulties may be mutually maintaining processes, particularly for individuals who suffer from poor sleep. Findings also raise the potential importance of targeting physical activity and sleep concurrently in interventions aimed at improving physical and mental health.

  View details for DOI 10.1016/j.mhpa.2014.05.003

  View details for PubMedID 25506392

  View details for PubMedCentralID PMC4260416

• Prevalence and clinical correlates of co-occurring insomnia and hypersomnia symptoms in depression. Journal of Affective Disorders Soehner, A. M., Kaplan, K. A., Harvey, A. G. 2014
• Insomnia comorbid to severe psychiatric illness. Sleep medicine clinics Soehner, A. M., Kaplan, K. A., Harvey, A. G. 2013; 8 (3): 361-371

  Abstract

  In psychiatric illness, there is a growing body of evidence indicating that sleep disturbances exert a detrimental influence on the course of these disorders and contribute to impaired function. Even when psychiatric disorders are successfully treated or stabilized, insomnia and other sleep disturbances often fail to remit. The present review focuses on sleep in two severe mental illnesses, namely bipolar disorder and schizophrenia. This article discusses the role of sleep disturbances and altered sleep architecture in relation to symptom status, functional impairment, quality of life, and the course of these disorders. Current evidence regarding pharmacological and psychological treatment approaches for insomnia in these populations is presented. This review also notes considerations for adapting Cognitive Behavioral Therapy for insomnia (CBT-I) procedures for severe mental illness and proposes directions for future research.

  View details for PubMedID 25302060

• Treatment of sleep disturbance Clinical handbook of psychological disorders Kaplan, K. A., Harvey, A. G. Guilford Press. 2013; 5
• Cognitive therapy for insomnia Encyclopedia of Sleep Soehner, A. M., Kaplan, K. A., Kanady, J., Harvey, A. G. Academic Press. 2013: 290–295
• Behavioral treatment of insomnia in bipolar disorder. American Journal of Psychiatry Kaplan, K. A., Harvey, A. G. 2013; 7 (170): 716-720
• Restless Pillow, Ruffled Mind: Sleep and Affect Coupling in Interepisode Bipolar Disorder JOURNAL OF ABNORMAL PSYCHOLOGY Gershon, A., Thompson, W. K., Eidelman, P., McGlinchey, E. L., Kaplan, K. A., Harvey, A. G. 2012; 121 (4): 863-873

  Abstract

  Disturbances in sleep and affect are prominent features of bipolar disorder, even during interepisode periods. Few longitudinal studies have prospectively examined the relationship between naturally occurring sleep and affect, and no studies to date have done so during interepisode periods of bipolar disorder and using the entire set of "gold standard" sleep parameters. Participants diagnosed with bipolar I disorder who were interepisode (n = 32) and healthy controls (n = 36) completed diagnostic and symptom severity interviews, and a daily sleep and affect diary, as well as an actigraphy sleep assessment, for eight weeks (M = 54 days, ± 8 days). Mutual information analysis was used to assess the degree of statistical dependence, or coupling, between time series data of sleep and affect. As measured by actigraphy, longer sleep onset latency was coupled with higher negative affect more strongly in the bipolar group than in the control group. As measured by sleep diary, longer wakefulness after sleep onset and lower sleep efficiency were coupled with higher negative affect significantly more strongly in the bipolar group than in the control group. By contrast, there were no significant differences between groups in the degree of coupling between any measures of sleep and positive affect. Findings support the coupling of sleep disturbance and negative affect during interepisode bipolar disorder. Ongoing monitoring of sleep-affect coupling may provide an important target for intervention in bipolar disorder.

  View details for DOI 10.1037/a0028233

  View details for Web of Science ID 000311527700007

  View details for PubMedID 22845651

  View details for PubMedCentralID PMC3612504

• Social support and social strain in inter-episode bipolar disorder BIPOLAR DISORDERS Eidelman, P., Gershon, A., Kaplan, K., McGlinchey, E., Harvey, A. G. 2012; 14 (6): 628-640

  Abstract

  This study focused on social support and social strain and their cross-sectional associations with instabilities in sleep and social rhythms in inter-episode bipolar disorder (BD).Thirty-five adults diagnosed with inter-episode BD type I and 38 healthy controls completed measures of perceived social support and social strain. Group differences in support and strain were examined. Within the BD group, instabilities in sleep and social rhythms were assessed with 28 days of daily diary and actigraphy. Correlation and regression analyses were used to examine cross-sectional and prospective associations between social support, social strain, instabilities in sleep and social rhythms, and mood symptoms.The BD group reported lower social support and higher social strain than the control group. Additionally, social strain was positively correlated with manic and depressive symptoms in the BD group. Furthermore, there was a cross-sectional association between social support and more stable sleep on actigraphy in the BD group, although social support did not predict future sleep instability.These results indicate that inter-episode BD is associated with deficient social support and elevated social strain compared to controls, and that this may be due to persistent inter-episode mood symptoms. Social strain may be particularly important given its association with manic and depressive symptoms. The results also raise the possibility that sleep instability is related to poor social support in BD.

  View details for DOI 10.1111/j.1399-5618.2012.01049.x

  View details for Web of Science ID 000308286800006

  View details for PubMedID 22862999

• Double trouble? The effects of sleep deprivation and chronotype on adolescent affect JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY Dagys, N., McGlinchey, E. L., Talbot, L. S., Kaplan, K. A., Dahl, R. E., Harvey, A. G. 2012; 53 (6): 660-667

  Abstract

    Two understudied risk factors that have been linked to emotional difficulties in adolescence are chronotype and sleep deprivation. This study extended past research by using an experimental design to investigate the role of sleep deprivation and chronotype on emotion in adolescents. It was hypothesized that sleep deprivation and an evening chronotype would be associated with decreased positive affect (PA), increased negative affect (NA), and lower positivity ratios.  Forty-seven healthy adolescents (aged 10-15 for girls, 11-16 for boys) participated in a sleep deprivation and a rested condition. A subsample of 24 adolescents was selected on the basis of extreme morningness or eveningness scores (based on outer quartiles of scores on the Children's Morningness-Eveningness Preferences Scale). PA and NA were measured using the Positive and Negative Affect Schedule for Children, and positivity ratios were calculated by dividing PA by NA.  Participants reported less positive affect and lower positivity ratios when sleep deprived, relative to when rested. Evening chronotypes reported less positive affect and lower positivity ratios than morning chronotypes in both rested and sleep deprivation conditions.  These findings extend previous research by suggesting that adolescents are adversely impacted by sleep deprivation, and that an evening chronotype might serve as a useful marker of emotional vulnerability. Early intervention and prevention strategies can focus on improving sleep and on using chronotherapy principles to reduce eveningness.

  View details for DOI 10.1111/j.1469-7610.2011.02502.x

  View details for Web of Science ID 000304087900007

  View details for PubMedID 22188424

• Comparison between actigraphy, polysomnography and sleep diary in individuals with bipolar disorder Bipolar Disorders Kaplan, K. A., Talbot, L. S., Gruber, J., Harvey, A. G. 2012; 14: 870-879
• Interventions for Sleep Disturbance in Bipolar Disorder. Sleep medicine and psychiatric illness. Harvey, A. G., Kaplan, K. A., Soehner, A. M. Lippincott Williams & Wilkins. 2012
• The Effect of Sleep Deprivation on Vocal Expression of Emotion in Adolescents and Adults SLEEP McGlinchey, E. L., Talbot, L. S., Chang, K., Kaplan, K. A., Dahl, R. E., Harvey, A. G. 2011; 34 (9): 1233-1241

  Abstract

  Investigate the impact of sleep deprivation on vocal expression of emotion.Within-group repeated measures analysis involving sleep deprivation and rested conditions.Experimental laboratory setting.Fifty-five healthy participants (24 females), including 38 adolescents aged 11-15 y and 17 adults aged 30-60 y.A multimethod approach was used to examine vocal expression of emotion in interviews conducted at 22:30 and 06:30. On that night, participants slept a maximum of 2 h.Interviews were analyzed for vocal expression of emotion via computerized text analysis, human rater judgments, and computerized acoustic properties. Computerized text analysis and human rater judgments indicated decreases in positive emotion in all participants at 06:30 relative to 22:30, and adolescents displayed a significantly greater decrease in positive emotion via computerized text analysis relative to adults. Increases in negative emotion were observed among all participants using human rater judgments. Results for the computerized acoustic properties indicated decreases in pitch, bark energy (intensity) in certain high frequency bands, and vocal sharpness (reduction in high frequency bands > 1000 Hz).These findings support the importance of sleep for healthy emotional functioning in adults, and further suggest that adolescents are differentially vulnerable to the emotional consequences of sleep deprivation.

  View details for DOI 10.5665/SLEEP.1246

  View details for Web of Science ID 000294481700014

  View details for PubMedID 21886361

• Hypersomnia in interepisode bipolar disorder: Does it have prognostic significance? Journal of Affective Disorders Kaplan, K. A., Gruber, J., Eidelman, P., Talbot, L. S., Harvey, A. G. 2011; 132 (3): 438-44
• Sleep Deprivation in Adolescents and Adults: Changes in Affect EMOTION Talbot, L. S., McGlinchey, E. L., Kaplan, K. A., Dahl, R. E., Harvey, A. G. 2010; 10 (6): 831-841

  Abstract

  The present study investigated the impact of sleep deprivation on several aspects of affective functioning in healthy participants selected from three different developmental periods: early adolescence (ages 10-13), midadolescence (ages 13-16), and adulthood (ages 30-60). Participants completed an affective functioning battery under conditions of sleep deprivation (a maximum of 6.5 hours total sleep time on the first night followed by a maximum of 2 hours total sleep time on the second night) and rest (approximately 7-8 hours total sleep time each night for two consecutive nights). Less positive affect was observed in the sleep-deprived, compared to rested, condition. This effect held for 9 of the 12 positive affect items on the PANAS-C. Participants also reported a greater increase in anxiety during a catastrophizing task and rated the likelihood of potential catastrophes as higher when sleep deprived, relative to when rested. Early adolescents appraised their main worry as more threatening when sleep deprived, relative to when rested. These results support and extend previous research underscoring the adverse affective consequences of sleep deprivation.

  View details for DOI 10.1037/a0020138

  View details for Web of Science ID 000286125600008

  View details for PubMedID 21058849

• Hypersomnia across mood disorders: A review and synthesis Sleep Medicine Reviews Kaplan, K. A., Harvey, A. G. 2009; 13: 275-285
• Cognitive mechanisms in chronic insomnia: Processes and prospects. Sleep Medicine Clinics Kaplan, K. A., Talbot, L. S., Harvey, A. G. 2009; 4 (4): 541-548
• Relationship between awareness of sleepiness and ability to predict sleep onset: Can drivers avoid falling asleep at the wheel? Sleep Medicine Kaplan, K. A., Itoi, A., Dement, W. C. 2007; 9 (1): 71-79
• The impact of extended sleep on daytime alertness, vigilance, and mood SLEEP MEDICINE Kamdar, B. B., Kaplan, K. A., Kezirian, E. J., Dement, W. C. 2004; 5 (5): 441-448

  Abstract

  To measure the effects of prolonged sleep extension on daytime alertness, vigilance, and mood in healthy young adults. Little research has documented the effects of increased sleep on daytime function despite a high prevalence of daytime fatigue and sleepiness in the adult population. Past extension studies report conflicting results with regard to Multiple Sleep Latency Test (MSLT) scores, vigilance, and mood ratings. No study has challenged subjects to maximum sleep extension, defined by an MSLT score of 20.Fifteen healthy college students reporting minimal daytime sleepiness were allowed to sleep as much as possible during a sleep extension period. MSLT scores, psychomotor vigilance task (PVT) reaction times, and profile of mood states (POMS) ratings were measured at baseline, mid-extension, and end-extension.There was a significant increase in both journal and actigraphy sleep totals during all extension segments (P<0.01). MSLT scores increased significantly from baseline to both mid- and end-extension (P<0.01). Five of eight tabulated PVT measures also improved significantly at mid- and end-extension with respect to baseline (P<0.05). POMS vigor and fatigue scores showed a similar improvement (P<0.01). Seven subjects achieved an MSLT score of 20. Six subjects showed substantial improvements while two subjects obtained relatively little extra sleep and showed little or no MSLT improvement. The maximum extension group displayed exceptional improvements in vigilance and POMS ratings.Extended sleep leads to substantial improvements in daytime alertness, reaction time, and mood.

  View details for DOI 10.1016/j.sleep.2004.05.003

  View details for Web of Science ID 000224018100004

  View details for PubMedID 15341888

• The impact of extra sleep on daytime alertness, vigilance, and mood. Sleep Medicine Kamdar, B. B., Kaplan, K. A., Kezirian, E. J., Dement, W. C. 2004; 5: 441-448