Old age sleep
The total sleep time during the night is reduced, but if daytime naps are frequent or prolonged, the total amount of sleep during each 24 h may be similar to that of younger subjects. The sleep ef?ciency falls to 70–80% with an increase in the number of awaken-ings and a reduction in stages 3 and 4 NREM sleep [13]. This is around 18% at age 20 years, but may be only around 10% at the age of 60 and by 75 there may be no stage 4 NREM sleep, especially in males. The amplitude of the delta waves falls by about 75% relative to childhood, probably as a result of loss of cortical synchronization due to degeneration of the sleep regulating processes and to cerebral atrophy which causes fewer cortical neurones to be sampled by the surface electroencephalogram (EEG). The duration of (more…)
