figure1

Figure 1. Effects of age on normal sleep cycles. REM sleep (darkened area) occurs cyclically throughout the night at intervals of approximately 90 minutes in all age groups. REM sleep decreases slightly in the elderly, whereas stage 4 sleep decreases progressively with age, so that little, if any, is present in the elderly. In addition, the elderly have frequent awakenings and a notable increase in wake time after sleep onset.