Paying down the Sleep Debt: Realization of Benefits during Subsequent Sleep Restriction and Recovery

The study objective was to determine whether sleep extension (a) improves alertness and performance during subsequent sleep restriction and (b) mediates the rate at which alertness and performance are restored by postrestriction recovery sleep. Twenty-four healthy adult participants (ages 18-39) were randomly assigned to an Extended [10 hours time in bed (TIB)] or Habitual [mean (SD) = 7.09 (0.7)] sleep group for one week, followed by one Baseline (10 hours or habitual TIB), seven Sleep Restriction (3 hours TIB), and five Recovery Sleep nights (8 hours TIB) with performance [Psychomotor Vigilance Task (PVT)] and alertness [Maintenance of Wakefulness Test (MWT); Stanford Sleepiness Scale (SSS)] tests administered hourly throughout. We conclude that the extent to which sleep restriction impairs alertness and performance, and the rate at which these impairments are subsequently reversed by recovery sleep, varies as a function of the amount of nightly sleep obtained prior to the sleep restriction period.