The dynamic responses of mood and sleep physiology to chronic sleep restriction and subsequent recovery sleep.

Healthy sleep of sufficient duration preserves mood and disturbed sleep is a risk factor for a range of psychiatric disorders. As adults commonly experience chronic sleep restriction (SR), an enhanced understanding of the dynamic relationship between sleep and mood is needed, including whether susceptibility to SR-induced mood disturbance differs between sexes. To address these gaps, data from N = 221 healthy adults who completed one of the two multi-day laboratory studies with identical 9-day SR protocols were analyzed. Participants randomized to the SR (n = 205) condition underwent 5 nights of SR to 4 hours of time-in-bed and were then randomized to one of the seven sleep doses that ranged from 0 to 12 hours in 2 hours increments; participants randomized to the control (n = 16) condition received 10 hours time-in-bed on all study nights. The Profile of Mood States (POMS) was used to assess mood every 2 hours during wakefulness and markers of sleep homeostasis (EEG slow-wave activity (SWA)) were derived via polysomnography. Mood progressively deteriorated across SR with marked disturbances in somatic mood components. Altered sleep physiology contributed to mood disturbance whereby increased EEG SWA was associated with increased POMS Total Mood Disturbance scores, a finding specific to males. The mood was restored in a dose-response fashion where improvements were greater with longer sleep doses. These findings suggest that when lifestyle and environmental factors are inhibited in the laboratory, the affective consequences of chronic sleep loss are primarily somatic mood disturbances. Altered sleep homeostasis may contribute to mood disturbance, yet sleep-dependent mechanisms may be sex-specific.