Introduction

Sleep disorders impair the ability to fall or stay asleep, involve excessive sleep, disrupt circadian sleep rhythms, or cause abnormal sleep-related behavior.

Geriatric Essentials

• With aging, the proportion of total sleep time spent in deep (stage 3 or 4) nonrapid eye movement sleep decreases.
• The elderly tend to have more difficulty falling and staying asleep than younger adults.
• The elderly tend to fall asleep earlier in the evening and awaken earlier in the morning.
• With aging, recovery from disturbances in the sleep-wake cycle and in circadian rhythms tends to become more difficult.
• Many drugs commonly used by the elderly and many disorders common among the elderly can disturb sleep.
• Because sleep disorders are common among the elderly, health care practitioners should screen all elderly patients by asking a few questions.

Up to 50% of elderly people report problems with sleep, especially difficulty falling or staying asleep. Factors that commonly contribute include psychologic stressors (eg, bereavement, posttraumatic stress, forced retirement, social isolation, lack of community involvement), physical disorders, mental disorders (eg, anxiety, dementia, depression), and adverse effects of drugs (see Table 47-1). Sedative-hypnotics can be particularly problematic. Because many elderly people have difficulty falling or staying asleep, sedative-hypnotic use is more common among the elderly than among younger people. Elderly people can develop the same circadian rhythm sleep disorders as younger people.

Sleep Physiology

Sleep structure relates the stages and cycles of sleep, which involve 2 types of sleep: nonrapid eye movement (NREM) and rapid eye movement (REM). NREM sleep seems to be more important for physical recuperation; deprivation causes symptoms such as muscle aches and fatigue. REM sleep seems to be more important for mental and psychologic recuperation; deprivation causes symptoms such as irritability and poor concentration.

Normally, NREM and REM sleep alternate throughout the night in 5 or 6 cycles. NREM sleep has 4 stages that range in depth from stage 1 (the earliest and lightest level, when waking the sleeper is easy) to stage 4 (the deepest level, when waking the sleeper is difficult). During stage 1, transient arousals (2- to 15-sec awakenings) occur; on EEG, they are characterized by alpha-wave intrusions into sleep. Stage 2 sleep is characterized by relatively low-voltage, mixed-frequency background activity on EEG; so-called sleep spindles and K complexes also occur. Stages 3 and 4 are often referred to as slow-wave or deep sleep; high-voltage, slow (delta)-wave activity is characteristic. About 75 to 80% of total sleep time is spent in NREM sleep, with about 15 to 20% of total sleep time spent in stages 3 and 4 NREM sleep.

In REM sleep, bursts of rapid eye movement are a key feature. Rate and depth of breathing and often heart rate and BP increase. Normally during REM sleep, skeletal muscles are virtually paralyzed, and muscle tone is very low. At least 85% of dreaming occurs during REM sleep. REM sleep is characterized by low-voltage, mixed-frequency activity on EEG. About 20 to 25% of total sleep time is spent in REM sleep.

Effects of Aging on Sleep

Experts disagree on which changes in sleep occur normally with aging.

Time spent in stage 1 NREM sleep may increase from 5% in younger adults to 12 to 15% in the elderly, perhaps because the elderly have more transient arousals during the night. In stage 2 NREM sleep, the number of sleep spindles and K complexes may decrease with aging. Time spent in stages 3 and 4 NREM sleep decreases with aging, possibly beginning as early as age 20; characteristic high-voltage, delta-wave activity may almost cease in extreme old age. Stages 3 and 4 NREM sleep may be better preserved in elderly women than in elderly men. The net effect of age-related changes in NREM sleep is less time spent in the deep, most restorative stages.

Evidence for an age-related decrease in REM sleep time is inconsistent. The proportion of REM sleep time may be preserved in the elderly, but the absolute amount may decrease because total nocturnal sleep time may be reduced. This decrease may result in irritability and possibly in impaired cognition.

Evidence for age-related changes in total sleep time (decreased, increased, no change) is inconsistent. The need for sleep probably does not decrease with aging. However, sleep efficiency (time asleep vs time in bed) decreases from 95% during adolescence to < 80% during old age; nocturnal sleep latency (time to fall asleep) is often prolonged in the elderly. The elderly tend to feel sleepy and fall asleep earlier in the evening and awaken earlier in the morning. The elderly tend to be less tolerant of shifts in the sleep-wake cycle (eg, those due to jet lag). Daytime napping may compensate for poor nocturnal sleep but may disrupt the sleep-wake cycle, contributing to poor nocturnal sleep.

Screening

A long-standing National Institutes of Health consensus statement on sleep disorders in the elderly has recommended that health care practitioners screen elderly people by asking the following:

• Are they satisfied with their sleep?
• Does sleep or fatigue interfere with activities?
• Does their bed partner or another person notice unusual behavior (eg, snoring, interrupted breathing, leg movements) in them during sleep?

This topic was last updated March 2006.