(REM = rapid eye movement)Several generalizations can be made regarding aging and sleep characteristics.
For optimal daytime alertness, humans require an average of about eight hours of sleep for a 24-hour period.
Sleep deprivation causes increased sleepiness and may cause cognitive impairment.
It is now well established that a person's circadian rhythm is strongly influenced by exposure to light.
Normal sleep progresses through a number of stages during each sleep period.
Poor sleep habits such as irregular sleep-wake times and daytime napping may contribute to insomnia.