Napping promotes inter-session habituation to emotional stimuli

Area of Science:

• Cognitive Neuroscience
• Sleep Research
• Psychophysiology

Background:

• Emotional stimuli elicit robust physiological responses.
• Habituation, a decrease in response to repeated stimuli, is crucial for emotional regulation.
• The impact of daytime napping on emotional habituation remains underexplored.

Purpose of the Study:

• To investigate the effect of a daytime nap on inter-session habituation to aversive visual stimuli.
• To examine the role of sleep stages (SWS, REM) in modulating emotional habituation.
• To compare physiological and subjective habituation responses.

Main Methods:

• Healthy young adults viewed negative and neutral International Affective Picture System (IAPS) images across two sessions.
• Physiological measures included skin conductance response (SCR), heart-rate deceleration (HRD), and corrugator supercilii EMG.
• Participants underwent a nap or a quiet wake period between sessions; sleep was polysomnographically monitored.

Main Results:

• Nap subjects showed greater inter-session habituation in SCR and EMG for repeated negative stimuli compared to wake subjects.
• Sleep, specifically SWS, correlated with enhanced EMG habituation, while REM sleep trended with reduced SCR habituation to negative stimuli.
• Subjective ratings did not differ between groups, but physiological habituation to aversive images was enhanced by napping.

Conclusions:

• Daytime napping, particularly stages like SWS, can promote physiological emotional adjustment.
• Sleep facilitates inter-session habituation to aversive stimuli at a physiological, but not subjective, level.
• These findings highlight sleep's role in emotional regulation and processing of negative experiences.