Please cite this article in press as: Neu D, et al. Does more sleep matter? Differential effects of NREM- and REM-dominant sleep on sleepiness and vigilance. Neurophysiologie Clinique/Clinical Neurophysiology (2015), http://dx.doi.org/10.1016/j.neucli.2014.10.004 ARTICLE IN PRESS +Model NEUCLI-2476; No. of Pages 9 Neurophysiologie Clinique/Clinical Neurophysiology (2015) xxx, xxx—xxx Disponible en ligne sur ScienceDirect www.sciencedirect.com ORIGINAL ARTICLE/ARTICLE ORIGINAL Does more sleep matter? Differential effects of NREM- and REM-dominant sleep on sleepiness and vigilance Est-ce mieux de dormir plus ? Effets différentiels du sommeil lent et du sommeil paradoxal sur la somnolence et la vigilance D. Neu a,*,b,c , O. Mairesse a,b,d,e , J. Newell a , P. Verbanck a,b , P. Peigneux f , G. Deliens a,f a Brugmann University Hospital, U.L.B./V.U.B, Sleep Laboratory & Unit for Chronobiology U78, Arthur Van Gehuchten Square, Building Hh, 1020 Brussels, Belgium b UNI, ULB Neurosciences Institute, Faculty of Medicine, Laboratory for Medical Psychology ULB312, Université Libre de Bruxelles (U.L.B.), Brussels, Belgium c Center for the Study of Sleep Disorders, Edith Cavell Medical Institute, CHIREC, Brussels, Belgium d Department of Experimental and Applied Psychology (EXTO), Vrije Universiteit Brussel (V.U.B.), Brussels, Belgium e Royal Military Academy (R.M.A.), Department LIFE, Brussels, Belgium f UR2NF, Neuropsychology and Functional Neuroimaging Research Group at CRCN - Center for Research in Cognition and Neurosciences, Université Libre de Bruxelles (ULB) and UNI - ULB Neurosciences Institute, Brussels, Belgium Received 12 April 2014; accepted 25 October 2014 KEYWORDS NREM sleep; REM sleep; Sleepiness; Psychomotor vigilance test; Visual analog scale; Split-night Summary We investigated effects of NREM and REM predominant sleep periods on sleepiness and psychomotor performances measured with visual analog scales and the psychomotor vig- ilance task, respectively. After one week of stable sleep-wake rhythms, 18 healthy sleepers slept 3 hours of early sleep and 3 hours of late sleep, under polysomnographic control, spaced by two hours of sustained wakefulness between sleep periods in a within subjects split-night, sleep interruption protocol. Power spectra analysis was applied for sleep EEG recordings and sleep phase-relative power proportions were computed for six different frequency bands (delta, theta, alpha, sigma, beta and gamma). Both sleep periods presented with similar sleep duration and efficiency. As expected, phasic NREM and REM predominances were obtained for early and late sleep conditions, respectively. Albeit revealing additive effects of total sleep duration, our results showed a systematic discrepancy between psychomotor performances and sleepiness ∗ Corresponding author. Tel.: +2 0 2 4772554; fax: +32 0 2 4772162. E-mail address: daniel.neu@chu-brugmann.be (D. Neu). http://dx.doi.org/10.1016/j.neucli.2014.10.004 0987-7053/© 2015 Elsevier Masson SAS. All rights reserved.