Can normal subjects be motivated to fall asleep faster?

Abstract

The Multiple Sleep Latency Test (MSLT) is widely believed to offer an objective, physiological measure of sleepiness. The speed with which a person falls asleep throughout the day is understood to be related systematically to sleep need and circadian phase. This study examined whether normal subjects ( n = 14 young female adults) could achieve faster MSLT sleep onsets if they were given the incentive to do so. During week 1 baseline MSLTs were determined over 1 day for all subjects. In week 2 they were randomly assigned to two groups. Control subjects underwent a second MSLT testing day identical to that of week 1, whereas Incentive subjects had an additional financial incentive to sleep. There was a significant reduction in sleep onset latency (indicating increased sleepiness) during the 1500 h trial following the incentive, when subjects also reported a significantly greater increase in sleepiness over the trial. These findings suggest that when coupled with a mid-afternoon increase in sleepiness, increased motivation to sleep can reduce sleep onset latency.