As every sleep researcher knows, the surest way to hear complaints about sleep is to ask the elderly.
"Older people complain more about their sleep; they just do," said Michael Vitiello, a sleep researcher who is a professor of psychiatry and behavioural sciences at the University of Washington.

And for years, sleep scientists thought they knew what was going on: sleep starts to deteriorate in late middle age and steadily erodes from then on. It seemed so obvious that few thought to question the prevailing wisdom.
Now, though, new research is leading many to change their minds.

To researchers' great surprise, it turns out that sleep does not change much from age 60 on. And poor sleep, it turns out, is not because of aging itself, but mostly because of illnesses or the medications used to treat them.

"The more disorders older adults have, the worse they sleep," said Sonia Ancoli-Israel, a professor of psychiatry and a sleep researcher at the University of California, San Diego. "If you look at older adults who are very healthy, they rarely have sleep problems."

And new studies are indicating that poor sleep may circle back to cause poor health. At least when it comes to pain, a common cause of disrupted sleep, a restless night can make pain worse the next day. Then with worse pain, sleep may become even more difficult -- a vicious cycle common in people with conditions that tend to afflict the elderly, like back pain and arthritis.

The new view of sleep emerged from two parallel lines of research. The first asked what happened to sleep patterns when healthy people grew old. The second sought to uncover the relationship between sleep and pain.
To find out what happens with aging, some investigators, including Vitiello, studied older people who reported no sleep problems.

They actually make up a large group -- nearly half of people over 65. Were these people somehow spared age-related changes in sleep?

They were not. Their sleep turned out to be different from sleep in young people: it was lighter, more often disrupted by brief awakenings, and shorter by a half hour to an hour. Vitiello reasoned that the age-related changes in sleep patterns might not be an issue in themselves. Something else was making people complain about their sleep.

Over a life span

Vitiello and his colleagues also asked what normally happened to sleep over the life span. It had long been known that sleep changes, but no one had systematically studied when those changes occurred or how pronounced they were in healthy people.

With analysis of 65 sleep studies, which included 3,577 healthy subjects ages 5 to 102, the investigators had their next surprise. Most of the changes in sleep patterns occurred when people were between the ages of 20 and 60. Compared with teenagers and young adults, healthy middle-aged and older people slept a half hour to an hour less each night, they woke up a bit more often during the night, and their sleep was lighter. But after age 60, there was little change in sleep, at least in people who were healthy.

And even though sleep changed during adulthood, many of the changes were subtle. Middle-aged and older people, for example, did not have more difficulty falling asleep. The only change in sleep latency, as it is called, emerged when the investigators compared latency at the two extremes, in 20- and 80-year-olds. The 80-year-olds took an average of 10 more minutes to fall asleep.

Contrary to their expectations, the investigators found no increase in daytime drowsiness in healthy older people. Nor did aging affect the time it took for people to start dreaming after they fell asleep.
Instead, the biggest change was the number of times people woke after having fallen asleep.