ABSTRACT
Why do aged people often not sleep for a long time? Diverse physiological changes occur due to aging. Sleep also changes with age and, as a result, instances of early evening sleep increase and instances of sleep at dawn decrease. The reason for this advancement of sleeping time is that the cycle of the living body clock, which adjusts the time for falling asleep is shortened. Meanwhile, awakening at dawn and suffering from difficulties in falling asleep again will not be experienced if a long sleep is taken, even if the time for falling asleep has been advanced. However, elderly people cannot sleep for a long time because although non-rapid eye movement (REM) sleep and REM sleep are repeated in 90-minute cycles, non-REM sleep (deep sleep) decreases with age, while REM sleep increases with age. In childhood and adolescence, the ratio of slow-wave sleep (deep sleep in which growth hormone is secreted) is high. Elderly people, having shallow sleep, frequently awake to twist and turn and then eventually awake completely. Second, elderly people take many naps, whereas children aged less than five years old twice a day. However, children who are becoming adults exhibit a long sleep only at night and, upon attaining an age older than 55 years feel sleepy often and take naps even during the day. As a result, they cannot have a deep sleep at night.
