title: Does more sleep matter? Differential effects of NREM- and REM-dominant sleep on sleepiness and vigilance.
abstract: We investigated effects of NREM and REM predominant sleep periods on sleepiness and psychomotor performances measured with visual analog scales and the psychomotor vigilance task, respectively. After one week of stable sleep-wake rhythms, 18 healthy sleepers slept 3hours of early sleep and 3hours 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 levels. In addition, sleepiness remained stable throughout sustained wakefulness during both conditions, whereas psychomotor performances even decreased after the second sleep period. Disregarding exchanges for frequency bands in NREM or stability in REM, correlations between outcome measures and EEG power proportions further evidenced directional divergence with respect to sleepiness and psychomotor performances, respectively. Showing that the functional correlation pattern changed with respect to early and late sleep condition, the relationships between EEG power and subjective or behavioral outcomes might however essentially be related to total sleep duration rather than to the phasic predominance of REM or NREM sleep.
authors.affiliation: Brugmann University Hospital, U.L.B./V.U.B, Sleep Laboratory & Unit for Chronobiology U78, Arthur Van Gehuchten Square, Building Hh, 1020 Brussels, Belgium; UNI, ULB Neurosciences Institute, Faculty of Medicine, Laboratory for Medical Psychology ULB312, Université Libre de Bruxelles (U.L.B.), Brussels, Belgium; Center for the Study of Sleep Disorders, Edith Cavell Medical Institute, CHIREC, Brussels, Belgium. Electronic address: daniel.neu@chu-brugmann.be.
authors.forename: D
authors.initials: D
authors.lastname: Neu
authors.affiliation: Brugmann University Hospital, U.L.B./V.U.B, Sleep Laboratory & Unit for Chronobiology U78, Arthur Van Gehuchten Square, Building Hh, 1020 Brussels, Belgium; UNI, ULB Neurosciences Institute, Faculty of Medicine, Laboratory for Medical Psychology ULB312, Université Libre de Bruxelles (U.L.B.), Brussels, Belgium; Department of Experimental and Applied Psychology (EXTO), Vrije Universiteit Brussel (V.U.B.), Brussels, Belgium; Royal Military Academy (R.M.A.), Department LIFE, Brussels, Belgium.
authors.forename: O
authors.initials: O
authors.lastname: Mairesse
authors.affiliation: Brugmann University Hospital, U.L.B./V.U.B, Sleep Laboratory & Unit for Chronobiology U78, Arthur Van Gehuchten Square, Building Hh, 1020 Brussels, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Newell
authors.affiliation: Brugmann University Hospital, U.L.B./V.U.B, Sleep Laboratory & Unit for Chronobiology U78, Arthur Van Gehuchten Square, Building Hh, 1020 Brussels, Belgium; UNI, ULB Neurosciences Institute, Faculty of Medicine, Laboratory for Medical Psychology ULB312, Université Libre de Bruxelles (U.L.B.), Brussels, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Verbanck
authors.affiliation: 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.
authors.forename: P
authors.initials: P
authors.lastname: Peigneux
authors.affiliation: Brugmann University Hospital, U.L.B./V.U.B, Sleep Laboratory & Unit for Chronobiology U78, Arthur Van Gehuchten Square, Building Hh, 1020 Brussels, Belgium; 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.
authors.forename: G
authors.initials: G
authors.lastname: Deliens
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D058256:Brain Waves; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D011597:Psychomotor Performance; D011930:Reaction Time; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
keywords: NREM sleep; Nuit coupée; Psychomotor vigilance test; REM sleep; Sleepiness; Sommeil lent (SL); Sommeil paradoxal (SP); Somnolence; Split-night; Test psychomoteur de vigilance; Visual analog scale; Échelle visuelle analogique