Sleep restriction alters physiological and emotional responses to emotion induction.

Habitual insufficient sleep has long-term health consequences via its impact on autonomic nervous system (ANS) function and on regulation of emotion. To our knowledge, the effects of insufficient sleep on emotion-induced ANS function have not been tested. The present study aimed to address this lacuna. Using an emotion induction procedure, the effects of sleep restriction on physiological responses to validated neutral and sad film clips were assessed in a two-by-two, pseudo-randomized, cross-over design. Thirty-one participants, aged 20-33 years, were assessed after sleeping for either 5 h (sleep restricted, SR) or 8 h (well rested, WR) per night, for three consecutive nights. Physiological measures included heart rate, heart rate variability, skin conductance response (SCR) and participants' ratings of affect and fatigue. There was no effect of sleep conditions on self-reported negative affect, but watching the sad clip reduced self-reported fatigue in the SR condition. There was greater heart rate deceleration while watching sad relative to neutral clips, independent of the sleep condition. Sleep restriction increased heart rate variability measures, with no effect of emotion induction. There was an interaction of emotion induction with sleep condition for SCR, with more SCRs to sad relative to neutral clips in the WR condition, and the opposite effect in the SR condition. Combined, the results suggest that the ANS response to an emotional cue was altered by sleep restriction. The results suggest an adaptive ANS response to mild, chronic sleep restriction, resulting in constant heart rate response and self-reported experience across WR and SR conditions, despite mounting fatigue.