With Aging, Healthy Adults Need Less Sleep


Researchers have found that progressively getting less than eight hours of sleep a night as we get older may be a normal part of healthy aging, according to a new study conducted at the University of Surrey in England and published in the journal Sleep.

The study followed 110 healthy adults without chronic sleep complaints such as insomnia for four consecutive nights using polysomnography. Healthy older adults (aged 66 to 83) slept about 20 minutes less than middle-aged adults (between 40 and 55 years). Young people between 20 and 30 needed the most amount of sleep – about 23 minutes longer than the adults in mid-life. The average number of minutes spent in deep, slow-wave sleep also decreased with age.

In terms of hours, the older adults slept on average 6.5 hours during a normal night’s sleep, and displayed fewer symptoms of daytime sleepiness. The younger group slept a little over 7 hours. While the exact number of hours slept may be different under laboratory conditions than in real life, the take-home message is that it may be a natural part of aging to spend less time sleeping.


The second part of the study involved disrupting normal sleep patterns, which led to more daytime sleepiness among all three groups. Lead researcher stated, “Our findings reaffirm the theory that it is not normal for older people to be sleepy during the daytime. 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.”

The cause for the age-related reduction in sleep is still undetermined. Dr. Phyllis C. Zee, MD PhD, suggests that the body’s internal clocks change as we age and affect not only the length of time slept, but the amount of time spent in deep sleep and the nightly patterns of sleep. Older adults, for example, often fall asleep earlier in the evening and wake earlier in the morning than younger adults.

Some research has shown a genetic component to sleep patterns. A study published last August in the journal Science found that certain genes have roles in the body’s circadian rhythm, the natural sleep-wake cycle, and that a mutation to one of these genes called DEC2 can lead a person to routinely need less sleep.

A healthy amount of sleep is necessary for survival and for the ability to function both physically and mentally. Good sleep can enable a person to work productively, make sound judgments, avoid harm, recover from illness and socially interact with others. Also during sleep, the body secretes a growth hormone that repairs and regenerates cells and tissue throughout the body. The body also builds bone and muscle and strengthens the immune system during adequate sleep.