Sleep stage responses of older and younger subjects after sleep deprivation.

EEG sleep stage measures were obtained on younger subjects (18-22 years) and older subjects (40-50 years) at 9 a.m. after 2 nights of sleep loss. The first 200 min were compared. Both groups displayed sharply reduced latencies and increased stage 4 sleep. The proportionate distribution of stage amounts and numbers was not different. However, the younger group entered slow wave sleep more quickly.