Partial Sleep Deprivation Attenuates the Positive Affective System: Effects Across Multiple Measurement Modalities.

Ample behavioral and neurobiological evidence links sleep and affective functioning. Recent self-report evidence suggests that the affective problems associated with sleep loss may be stronger for positive versus negative affective state and that those effects may be mediated by changes in electroencepholographically measured slow wave sleep (SWS). In the present study, we extend those preliminary findings using multiple measures of affective functioning. In a within-subject randomized crossover experiment, we tested the effects of one night of sleep continuity disruption via forced awakenings (FA) compared to one night of uninterrupted sleep (US) on three measures of positive and negative affective functioning: self-reported affective state, affective pain modulation, and affect-biased attention. The study was set in an inpatient clinical research suite. Healthy, good sleeping adults (N = 45) were included. Results indicated that a single night of sleep continuity disruption attenuated positive affective state via FA-induced reductions in SWS. Additionally, sleep continuity disruption attenuated the inhibition of pain by positive affect as well as attention bias to positive affective stimuli. Negative affective state, negative affective pain facilitation, nor negative attention bias were altered by sleep continuity disruption. The present findings, observed across multiple measures of affective function, suggest that sleep continuity disruption has a stronger influence on the positive affective system relative to the negative affective affective system

Experimental sleep disruption and reward learning: moderating role of positive affect responses

Sleep disturbances increase vulnerability for depression, but the mechanisms underlying this relationship are not well known. We investigated the effects of experimental sleep disruption on response bias (RB), a measure of reward learning previously linked to depression, and the moderating role of positive affect responses. Participants (N = 42) were healthy adults enrolled in a within-subject crossover sleep disruption experiment that incorporated one night of uninterrupted sleep (US) and one night of forced awakenings (FA) in random order. On the day following each experimental sleep night, participants completed a probabilistic reward task to assess RB, and the Positive and Negative Affect Schedule-X. Participants were subgrouped according to positive affect responses: Preserved Positive Affect (i.e. positive affect scores maintained or increased; n = 15) or Reduced Positive Affect (i.e. positive affect scores decreased; n = 27) following FA. Contrary to our hypotheses, across participants, RB did not significantly differ between the US and FA sleep conditions (p = .67). However, the effect of sleep condition on RB was moderated by positive affect response (p = .01); those with preserved positive affect showed heightened RB following FA, whereas those with reduced positive affect showed diminished RB following FA. Changes in negative affect between US and FA did not moderate RB. The inability to preserve positive affect through periods of sleep disruption may be a marker of diminished reward learning capability. Understanding how sleep disruption impacts positive affect responses and reward learning identifies a pathway by which sleep disturbances may confer risk for depression