Introduction
napping, sleep curtailment, cognitive and affective benefits
Given the prevalence of sleep curtailment in modern society, scheduled napping is increasingly gaining traction as a remedy to counter the detrimental cognitive effects of chronic short nocturnal sleep [Previous work comparing different nap durations has mainly examined vigilance and speed of processing, and memory consolidation rather than memory encoding. These studies found that while very brief naps ranging from 30 sec to 5 min show low efficacy, naps of at least 10 min produce measurable benefits on tests of objective alertness [Three other variables are important in evaluating the utility of naps: sleep inertia on waking, and how sustained the cognitive and affective benefits are. Sleep inertia refers to the period immediately following wake in which a person’s arousal is temporarily lowered and performance may suffer [We sought to address these gaps in a fully within-participant design comparing polysomnographically monitored nap total sleep times of 10 min, 30 min, and 60 min with a wake control condition. Participants encoded pictures 90 min after waking and were tested on their memory 210 min later. Measures of self-reported alertness, mood, sustained vigilance, and speed of processing was serially evaluated at post-nap intervals of 5 min (to assess sleep inertia), 30 min, 60 min, and 240 min.