Experimental Conditions

We approached the problem of designing length-equivalent rest and sleep conditions by yoking the duration of a stimulus-free eyes-closed resting wake condition to the time that it took sleep participants to obtain a minimum of 10 mins of sleep. In this between-subjects design, condition (Sleep, Rest, or Active Wake) was assigned by triads, with the first participant in each triad assigned to the Sleep condition, the second to the Rest condition, and the third to the Active Wake condition. For each triad, experimental condition length was yoked to that of the Sleep participant, such that if the Sleep participant’s nap opportunity was 22 mins, the duration of the Rest and Active Wake condition would also be 22 mins. During the experimental phase room conditions were kept as similar as possible across the three conditions, except where differences are described below. Light levels were the same (lights on), the door was closed after the researcher started the session, and participants were video monitored during the experimental phase.

Participants were instructed to lie on the bed in the testing room and try to fall asleep, and to minimize movement. The light was left on and the door was closed. The interval ended when the participant had a) been in the room for 30 mins, b) had slept for 20 mins, or c) had fallen asleep and then woken up, but had been asleep for at least 10 mins and had been in the room for at least 20 mins. To be included in analysis for this condition, it was decided a priori that participants must obtain at least 10 total minutes of sleep. None of the participants in this sleep condition obtained REM sleep (see Table 2) and all sleep participants obtained N2 sleep.

Participant Information

Notes: P-values are based on a One-way ANOVA except: †=chi square statistic. *=significantly different between groups at p<0.05. ** HST=Average amount of sleep obtained per night by subject report. Means±SEMs.

Abbreviations: ESS, Epworth Sleepiness Scale; SSS, Stanford Sleepiness Scale.

Participants were instructed to sit upright against a pillow on the bed in the testing room, and to minimize movement, keep their eyes closed, and stay awake. The length of the interval was determined by the length of the yoked Sleep participant. To be included in analysis for this condition, it was decided a priori that participants must not obtain more than 2 mins of sleep during the interval, and that they not enter N2 sleep (ie, any sleep obtained was N1 sleep). Of the final Rest group included in analysis, N=5 slept, obtaining less than 2 mins of N1 sleep and no N2 sleep, and the remainder obtained no sleep.

Participants in this condition played the computer game Snood (http://snoodworld.com) at “medium” difficulty. They were instructed to play the game continuously, starting a new game each time they won or lost. The duration of game play was determined by the length of the yoked Sleep participant.