Sleep throughout adulthood

During young adulthood, sleep patterns usually seem stable but in fact are slowly evolving. Between age 20 and age 30, the amount of deep sleep drops by about half, and nighttime awakenings double. By age 40, the deepest stage of sleep has almost disappeared.

Women’s reproductive cycles can greatly influence sleep. During the first trimester of pregnancy, many women are sleepy all the time and may log an extra two hours a night if their schedules permit. As pregnancy continues, hormonal and anatomical changes reduce sleep efficiency so that less of a woman’s time in bed is actually spent sleeping. As a result, fatigue increases. The postpartum period usually brings dramatic sleepiness and fatigue — because the mother’s ability to sleep efficiently has not returned to normal, because she is at the mercy of her newborn’s rapidly cycling shifts between sleeping and waking, and because breast-feeding promotes sleepiness.

Women who aren’t pregnant may experience monthly shifts in sleep habits. During the second phase of the menstrual cycle, between ovulation and the next menses, some women fall asleep and enter rapid eye movement (REM) sleep, also known as dreaming sleep, more quickly than usual. A few experience extreme sleepiness. Investigators are probing the relationship between such sleep alterations, cyclic changes in body temperature, and levels of the hormone progesterone to see whether these physiologic patterns also correlate with premenstrual mood changes.

When men and women enter middle age, nighttime awakenings become more frequent and last longer. It’s particularly common for people to wake up after about three hours of sleep. During menopause, many women experience hot flashes that can interrupt sleep, sometimes leading to chronic insomnia. Obese people are more prone to nocturnal breathing problems, which often start during middle age. Here’s where it pays to be physically active. Men and women who are physically fit sleep more soundly as they grow older, compared with their sedentary peers.

Like younger people, older adults still spend about 20% of sleep time in REM sleep, but other than that, they sleep differently. Deep sleep accounts for less than 5% of sleep time, and in some people it is completely absent. Falling asleep takes longer, and the shallow quality of sleep results in dozens of awakenings during the night. Over a 24-hour period, however, older adults manage to accumulate the same amount of total sleep as younger people, thanks to napping. Doctors used to reassure older people that they needed less sleep than younger ones to function well, but sleep experts now know that isn’t true: It was a mistake scientists made when they failed to account for daytime naps logged by older folks. Generally, most sleep experts discourage napping, but if you find that you need a nap, it’s best to take one midday nap, rather than several brief ones scattered throughout the day and evening.

Sleep disturbances in elderly people, particularly in those who have Alzheimer’s disease or other forms of dementia, are very disruptive for caregivers. In one study, 70% of caregivers cited these problems as the decisive factor in seeking nursing home placement for a loved one. When caregivers of participants in adult day programs were interviewed, more than a third reported being distressed and sleep-deprived because they were looking after someone with disruptive nocturnal behaviors — such as insomnia, nightmares, wandering, physical aggression, loud screaming and talking, or calling for help. In a five-year test project in New York, adult day program participants are being treated for sleep disorders to see if therapy can increase the amount of time that they are able to remain at home.

Although sleep patterns inevitably change with age, older people need not lose alertness and pleasure in life because they can’t sleep. No matter how old you are, treatment of sleep disorders and do-it-yourself techniques to maximize sleep quality can bring improvement.

What kind of changes have you noticed in your sleep patterns as you age?

Need better sleep? Learn how to get it with Improving Sleep: A Guide to a Good Night's Rest. This special report from Harvard Medical School describes the factors that can disturb sleep, the latest in sleep research, and, most importantly, what you can do to get a good night's sleep. It also includes in-depth information on sleep disorders, including restless legs syndrome, narcolepsy, and sleep apnea.

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