Pilleriin Sikka is a postdoctoral research fellow in the Department of Psychology at Stanford University, a postdoctoral researcher in the Department of Psychology at the University of Turku (Finland), and a senior lecturer in cognitive neuroscience in the Department of Cognitive Neuroscience and Philosophy at the University of Skövde (Sweden). She holds a PhD degree in psychology (University of Turku, Finland), MSc degree in neuroscience (University of Oxford, UK), as well as MSc and BSc degrees in psychology (University of Tallinn, Estonia). Previously, she worked in the Department of Psychiatry at the University of Oxford (UK) in the field of molecular neuroscience. Pilleriin has received several prestigious research (e.g., Postdoctoral Reseach Award from the Finnish Foundations' Post Doc Pool) and teaching (The Golden Apple Award for Excellence in Teaching) awards as well as research grants (as a PI) from international and national foundations. She has more than ten years of teaching experience (courses in neuroscience, psychology, and well-being) and supervised as well as served as a mentor to many undergraduate and graduate students in the fields of psychology and cognitive neuroscience.

Honors & Awards

  • Merited Lecturer (awarded for excellence in research-based teaching), University of Skövde, Sweden (2022)
  • First Prize for PhD dissertation, Skaraborg’s Academy, Sweden (2021)
  • PhD Dissertation Award, The Finnish Sleep Research Society, Finland (2021)
  • Postdoctoral Fellowship, The Finnish Foundations' Post Doc Pool and the Emil Aaltonen Foundation (2020)
  • The Golden Apple Award for Excellence in Teaching, University of Skövde, Sweden (2020)
  • Best Poster Award, The Finnish Sleep Research Society, Finland (2018)
  • The Golden Apple Award for Excellence in Teaching, University of Skövde, Sweden (2015)
  • The Golden Apple Award for Excellence in Teaching, University of Skövde, Sweden (2010)
  • Winner of the Main Prize at the National Contest for University Students, Estonian Research Council (2005)
  • Winner of the Main Prize at the Contest of Students’ Research Papers, Tallinn University, Estonia (2005)
  • Harald Raudsep Scholarship, Estonian-Revelia Academic Fund, Maryland, USA (2005)
  • Kristjan Jaak Scholarship, Archimedes Foundation, Estonia (2005)
  • Kristjan Jaak Scholarship, Archimedes Foundation, Estonia (2004)
  • National Scholarship, Estonian Ministry of Education and Research, Estonia (2000)

Boards, Advisory Committees, Professional Organizations

  • Member, Society for Affective Science (SAS)
  • Member, International Society for Research on Emotion (ISRE)
  • Member, Association for the Scientific Study of Consciousness (ASSC)
  • Member, European Sleep Research Society (ESRS)
  • Member, Finnish Sleep Research Society (SUS)
  • Member, International Association for the Scientific Study of Dreams (IASD)

Professional Education

  • Ph.D., University of Turku (Finland), Psychology (2020)

Stanford Advisors

Current Research and Scholarly Interests

Pilleriin's main research interests focus on emotions and emotion regulation, mental well-being, sleep and dreaming, and consciousness. More specifically, she conducts research on the nature and continuity of emotions and emotion regulation across the wake-sleep cycle and how these are related to health and well-being. She also strives to understand the psychology and neurobiology of peace of mind as an aspect of mental well-being. In her research Pilleriin uses a multidisciplinary and multilevel framework that draws on the concepts, theories, and methods from the fields of philosophy, psychology, (affective) neuroscience, and (molecular) biology, and integrates different research areas, such as emotion research, sleep and dream research, consciousness research, and well-being research.

Lab Affiliations

All Publications

  • The Neural Bases of Expressive Suppression: A Systematic Review of Functional Neuroimaging Studies. Neuroscience and biobehavioral reviews Sikka, P., Stenberg, J., Vorobyev, V., Gross, J. J. 2022: 104708


    Expressive suppression refers to the inhibition of emotion-expressive behavior (e.g., facial expressions of emotion). Although it is a commonly used emotion regulation strategy with well-documented consequences for well-being, little is known about its underlying mechanisms. In this systematic review, we for the first time synthesize functional neuroimaging studies on the neural bases of expressive suppression in non-clinical populations. The 12 studies included in this review contrasted the use of expressive suppression to simply watching emotional stimuli. Results showed that expressive suppression consistently increased activation of frontoparietal regions, especially the dorsolateral and ventrolateral prefrontal cortices and inferior parietal cortex, but decreased activation in temporo-occipital areas. Results regarding the involvement of the insula and amygdala were inconsistent with studies showing increased, decreased, or no changes in activation. These mixed findings underscore the importance of distinguishing expressive suppression from other forms of suppression and highlight the need to pay more attention to experimental design and neuroimaging data analysis procedures. We discuss these conceptual and methodological issues and provide suggestions for future research.

    View details for DOI 10.1016/j.neubiorev.2022.104708

    View details for PubMedID 35636561

  • The dynamics of affect across the wake-sleep cycle: From waking mind-wandering to night-time dreaming. Consciousness and cognition Sikka, P., Valli, K., Revonsuo, A., Tuominen, J. 2021; 94: 103189


    Affective experiences occur across the wake-sleep cycle-from active wakefulness to resting wakefulness (i.e., mind-wandering) to sleep (i.e., dreaming). Yet, we know little about the dynamics of affect across these states. We compared the affective ratings of waking, mind-wandering, and dream episodes. Results showed that mind-wandering was more positively valenced than dreaming, and that both mind-wandering and dreaming were more negatively valenced than active wakefulness. We also compared participants' self-ratings of affect with external ratings of affect (i.e., analysis of affect in verbal reports). With self-ratings all episodes were predominated by positive affect. However, the affective valence of reports changed from positively valenced waking reports to affectively balanced mind-wandering reports to negatively valenced dream reports. These findings show that (1) the positivity bias characteristic to waking experiences decreases across the wake-sleep continuum, and (2) conclusions regarding affective experiences depend on whether self-ratings or verbal reports describing these experiences are analysed.

    View details for DOI 10.1016/j.concog.2021.103189

    View details for PubMedID 34419707