Less Sleep Normal Part of Aging?

Getting less sleep at night may be a normal part of healthy
aging and nothing to worry about for most healthy adults.

A new study shows that during a standard night of eight hours in bed the
amount of time spent actually sleeping decreases progressively with age.
Healthy older adults sleep about 20 minutes less than middle-aged adults, who
sleep 23 minutes less than young adults.

Researchers say the results suggest that healthy older adults without sleep
disorders should expect to sleep a little less at night without being sleepy
during the day.

"Our findings reaffirm the theory that it is not normal for older people to
be sleepy during the daytime," researcher Derk-Jan Dijk, PhD, professor of
sleep and physiology at the University of Surrey in England, says in a news
release. "Whether you are young or old, if you are sleepy during the day you
either don't get enough sleep or you may suffer from a sleep disorder."

Less Sleep Part of Healthy Aging

The study, published in Sleep, involved 110 healthy adults without
sleep complaints who were studied for one normal eight-hour sleep night
followed by two nights with or without sleep disruption followed by one
recovery night.

Among the participants, 44 were young (20 to 30 years old), 35 were
middle-aged (40 to 55) and 31 were older adults (66 to 83). Their sleep was
evaluated by polysomnography and monitored by researchers throughout the
experiment.

During the first normal sleep session, young adults slept an average of
433.5 minutes, middle-aged adults slept 410 minutes, and older adults slept 390
minutes. The average number of minutes spent in deep, slow-wave sleep also
decreased with age.

In addition, the average number of minutes spent awake after initially
falling asleep increased from 21 for young adults to 50 for middle-aged adults
and 71 for older adults.

Even though older adults got less total sleep at night than their younger
counterparts, researchers found that older adults displayed fewer symptoms of
daytime sleepiness. In a measure of daytime sleepiness, older adults took
five-and-a-half minutes longer to fall asleep after lying down compared to
younger adults.

The second part of the study, which involved disrupting the participants'
sleep, led to a similar response among the three age groups. They all showed
more signs of daytime sleepiness, and deep, slow-wave sleep rebounded during
the night of recovery sleep.

Researchers say healthy aging appears to be associated with a natural
reduction in sleep duration and depth needed to maintain daytime alertness.
They say the cause for age-related reduction in sleep still needs to be
established, but the findings could have important implications for older
adults complaining of insomnia who may not be aware of their reduced need for
sleep.

By Jennifer Warner
Reviewed by Louise Chang
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