The purpose of this study was to assess the level of sleepiness in individuals during and after partial chronic sleep restriction.

Excessive daytime sleepiness (EDS) is a common complaint in the general population, which is defined as the inability to stay awake and alert during the major waking episodes of the day. Limited studies have recorded the effects of partial chronic sleep restriction on objective measures of daytime somnolence.

Eighteen subjects underwent a sleep restriction and a control sleep sequence in random order. The sleep restriction sequence consisted of 3 nights of acclimation, then a 9 night experimental phase of restricted sleep (4 hours or less), followed by a 3 night recovery period of unrestricted sleep. In each phase, subjects underwent a maintenance of wakefulness test (MWT) and a single sleep latency test (SSLT) to determine objective daytime sleepiness during the sleep restricted and control sequence.

Partial chronic sleep restriction has a progressive impact on daytime sleepiness. However, after recovery sleep, daytime alertness is significantly recovered. These data may be helpful to further demonstrate the cumulative deleterious impact of chronic partial sleep restriction on daytime vigilance for patient counseling and public health initiatives concerning the importance of assuring sufficient sleep.