Participants sleep in lab while being monitored with polysomnography for 8 consecutive nights, including an adaptation night and a baseline night of 7.5 h time in bed (0:00-7:30). Afterwards, they are instructed to sleep in bed on a schedule alternated between 6 h, i.e. 1:30-7:30, and 9 h, i.e. 22:30-7:30).

Participants sleep in lab while being monitored with polysomnography for 8 consecutive nights of 7.5 h time in bed (0:00-7:30).

Experimental-induced sleep variability

As measured by the Stanford Sleepiness Scalen (SSS)

mood state as measured by the Positive and Negative Affect Scale (PANAS).

Sustained attention as measured by psychomotor vigilance task (PVT)

Processing speed as measured by Digit Symbol Substitution Test (DSST)

Inhibition as measured by stop-signal reaction time (SSRT)

working memory as measured by 2-back task

Actual sleep time, sleep onset latency, wake after sleep onset and night time arousals as measured by actigraphy and PSG. Sleep satisfactory and dreams as measured by sleep diary.