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Torhild T Pedersen,1 Erlend Sunde,2 Jonathan Wisor,3 Jelena Mrdalj,1 StÃ¥le Pallesen,2,4,5 Janne Grønli1 1Department of Biological and Medical Psychology, Faculty of Psychology, University of Bergen, Bergen, Norway; 2Department of Psychosocial Science, Faculty of Psychology, University of Bergen, Bergen, Norway; 3Sleep and Performance Research Center and Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, USA; 4Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway; 5Optentia Research Focus Area, North-West University, Vanderbijlpark, South AfricaCorrespondence: Torhild T Pedersen, Tel +4797007718, Email torhild.pedersen@uib.noPurpose: Millions of people work at times that overlap with the habitual time for sleep. Consequently, sleep often occurs during the day. Daytime sleep is, however, characterized by reduced sleep duration. Despite preserved time spent in deep NREM sleep (stage N3), daytime sleep is subjectively rated as less restorative. Knowledge on how night work influences homeostatic sleep pressure is limited. Therefore, we aimed to explore the effect of three consecutive simulated night shifts on daytime sleep and markers of sleep homeostasis.Patients and Methods: We performed continuous EEG, EMG and EOG recordings in the subjectsâ home setting for one nighttime sleep opportunity, and for the daytime sleep opportunities following three consecutive simulated night shifts.Results: For all daytime sleep opportunities, total sleep time was reduced compared to nighttime sleep. While time spent in stage N3 was preserved, sleep pressure at sleep onset, measured by slow wave activity (1â 4 Hz), was higher than nighttime sleep and higher on day 3 than on day 1 and 2. Elevated EEG power during daytime sleep was sustained through 6 h of time in bed. Slow wave energy was not significantly different from nighttime sleep after 6 h, reflecting a less efficient relief of sleep pressure.Conclusion: Adaptation to daytime sleep following three consecutive simulated night shifts is limited. The increased homeostatic response and continuation of sleep pressure relief even after 6 h of sleep, are assumed to reflect a challenge for appropriate homeostatic reduction to occur.Keywords: shift work, daytime sleep, sleep regulation, spectral analysis, sleep homeostasis |
