Several changes occur in the nature of sleep that ac- companies aging. The need for sleep remains about the same, but the character of sleep changes. Older adults ex- perience lighter, more interrupted sleep. They spend more time in Stage 1 than younger adults and also experience a decrease in Stages 3 and 4, the periods of deep, most restorative sleep. The amount of time in REM sleep stays about the same but occurs earlier in the sleep cycle.