Chronic Sleep Reduction: Daytime Vigilance Performance and EEG Measures of Sleepiness, With Particular Reference to “Practice” Effects

ABSTRACT Six pairs of young adult 8‐hr sleepers were divided equally into two groups, Reduction (R) and Control (C). They adhered to strict bed and arising times for six weeks. Additionally, R subjects reduced their sleep systematically to an average of 6 hrs per night. Following a baseline week, and on a weekly basis, “yoked” pairs of subjects, one from each group, were assessed for daytime sleepiness during prolonged vigilance performance, and by EEG measurement. All‐night sleep EEGs were taken on R subjects before and at the end of the reduction. There were no significant differences between the groups for any of the daytime sleepiness measures, but both groups displayed significant “practice” effects over the weeks. R subjects experienced no major difficulties, except for some tiredness around awakening and lunchtime. Overall daytime sleepiness was not increased. Reduction was at the expense of REM and stage 2 sleep, and led to significant declines in sleep onset latency and in stages W + 1 at nighttime. SWS was not affected. This level of reduction in young adults seems to be achieved relatively easily.