You May Need Less Sleep as You Get Older

A new study suggests that healthy older adults without sleep disorders may have a reduced "sleep need." The results were published in the Feb. 1 issue of the journal Sleep.

The U.K. study involved 110 healthy adults. They had no sleep disorders or sleep complaints. Their sleep was evaluated during an overnight sleep study.

Results show that total sleep time decreased with age. Older adults between 66 and 83 years of age slept about 20 minutes less than middle-aged adults and about 43 minutes less than young adults.

The study also found that the sleep of older adults was more fragmented and less intense. Awakenings during the night increased. And time spent in deep, slow-wave sleep decreased.

But it was younger adults who were sleepiest during the day. Older adults took longer to fall asleep during a daytime nap study.

"Our findings reaffirm the theory that it is not normal for older people to be sleepy during the daytime," lead author Derk-Jan Dijk, PhD, told the AASM. "If you are sleepy during the day you either don't get enough sleep or you may suffer from a sleep disorder."

In a 2008 study Dijk reported on the age-related reduction in the “maximal capacity for sleep.” Adults were allowed extended periods of sleep to determine their sleep need. The total daily sleep time of older adults (7.4 hours) ended up being 1.5 hours less than that of younger adults (8.9 hours).

It is unclear what may cause a change in the sleep need of older adults. The authors suggested that alterations in reproductive hormones or changes in the brain may be involved.

They added that the study did not address sleepiness during the evening hours. At that time of day older adults may be sleepier than young adults.

The authors also wrote that the results may help explain why some healthy older adults struggle with insomnia. They may be unaware of their reduced sleep need.

So insomnia may occur because they spend too much time in bed. “Sleep restriction” may help get their sleep back on track. This is one form of cognitive-behavioral therapy.

But it is important to note that many older adults have insomnia due to a medical condition. And they may have insomnia as a side effect of a medication.

Read more about sleep and older adults.

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How Much Sleep Do I Need?

UCLA researcher Jerry Siegel addressed this common question earlier in the week.

What’s the answer? One sleep size doesn’t fit all.

“Some people naturally sleep six hours,” he wrote. “And others naturally sleep eight hours.”

The better question is: Do you get enough sleep to remain alert and attentive during the day? And are you able to go to sleep and wake up without using alcohol, caffeine or other drugs?

If so, then you’re probably getting enough sleep.

But he warns that persistent daytime sleepiness is one sign that you may have a sleep disorder. And you should talk to a doctor if you have loud and frequent snoring. This is a common symptom of obstructive sleep apnea.

Last year an editorial by Siegel explored the nature and role of sleep.

Get help for an ongoing sleep problem at an AASM-accredited sleep center near you.

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We Sleep to Be Awake

In April the Sleep Education Blog examined the question of why we sleep. Research has been exploring complex answers to this simple question.

But a definitive explanation continues to be elusive; the question remains an “unsolved mystery.”

Now an editorial by UCLA’s Jerome Siegel suggests that sleep may not fulfill a universal function across all species. Instead sleep appears to be adaptive; its role may be based on “ecological variables” that differ from one species to another.

This would explain why the sleep habits of animals are so diverse, reports the Origins Blog. For example a brown bat sleeps more than 20 hours per day; but a giraffe only sleeps for about four hours.

Siegel views sleep as “a variant of dormant states” seen in both the plant and animal kingdoms. He proposes that sleep “optimizes the timing and duration of behaviour.”

So how and when an animal sleeps is based on its waking needs. The brown bat wakes up at the time of day when its food source is most plentiful; it’s the optimal time to eat.

Why do we sleep? Perhaps we need to understand why we are awake, Siegel suggests. That may be how we find the clues to the mystery of our need for sleep.

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Do All Animals Sleep?

Over the weekend a New York Times editorial longingly observed how “effortlessly” farm animals seem to sleep. In contrast, people seem to work at sleeping – or at avoiding sleep as much as possible.

“What a lot of shut-eye all the other species get, and how sleep-deprived humans seem in comparison!” the editorial lamented. “To grasp the force of human culture, all you have to do is consider how hard we try to organize our sleeping.”

One way researchers try to unlock the mysteries of human sleep is by studying sleep in other species. Results show a diversity of sleep habits.

A 2008 study involved brown-throated, three-toed sloths. The results emphasized the importance of studying animals in their natural environment.

In captivity sloths sleep for more than 16 hours per day, BBC News reported. But the study found that they only slept for 9.6 hours in the wild.

Last month BBC News reported on a study of fire ants. It found that queen ants fell asleep 90 times a day; these sleep periods lasted a little longer than six minutes. Their total daily sleep was more than nine hours.

In contrast, a single worker took 250 naps per day; each nap lasted just longer than a minute. Their total sleep was only 4 hours and 48 minutes a day.

The article added that this productivity may come with a cost: The worker ants only live for months; the queen ants live for years.

A 2009 study examined the sleep of dolphins. A dolphin only sends half of its brain to sleep; the other half remains conscious.

The dolphins in the study were able to remain vigilant over a five-day period, MSNBC reported. They also showed no signs of sleep deprivation.

It’s often assumed that every animal sleeps in one way or another. But is this true? Do all animals sleep?

It’s a difficult question to answer; it can be hard to tell whether an observed animal is sleeping or in a state of “quiet rest.”

UCLA’s Jerome Siegel published a review of the evidence in 2008. According to Siegel, we may be wrong to assume that there is a “universal state of sleep” among all animals.

“The evidence that all animals have a state that meets the accepted definitions of sleep is quite poor,” he concluded.

How much do animals sleep? Find out on the Neuroscience for Kids Web site.

Image by Alfonso Gonzalez

Sleep for Seven in 2009

So did you make a New Year’s resolution for 2009? Are you going to lose weight? Exercise more? Stop smoking?

We all know that resolutions can be hard to keep. It takes discipline to keep your commitment for the long haul. It also requires sleep.

Sleep? That’s right. Making sleep your top priority in 2009 will help you achieve all of your other goals. Your mind will be sharper and more focused. You’ll have more energy. You’ll feel better and more optimistic.

So maybe you should make a resolution to "Sleep for Seven." That is, to get at least seven hours of sleep, seven nights a week. The Seven Signs below are a good indicator of whether or not you need more sleep:

Seven Signs You May Need Seven Hours of Sleep in 2009

1. You’re dependent on an alarm clock.
2. You’re drowsy driving.
3. You’re attached to the coffee pot.
4. You’re making mistakes.
5. You’re forgetful.
6. You’re cranky, snippy and irritable.
7. You’re frequently getting sick.

How many of these seven signs describe you? What are you going to do to make sleep a higher priority in 2009?