Is the Circadian Rhythm Less Effective with Age?

We all know that sleep often becomes more difficult as we age. Some of us who've accumulated a certain number of birthday cards know this first hand! We also know that our circadian "clocks"—an internal mechanism that keeps us on a 24-hour, night-day cycle—function less well with age, and this contributes to sleep problems that can plague older adults, including:

• Difficulty falling asleep
• Trouble staying asleep
• Problems with daytime alertness

In addition to difficulty with nightly sleep, as we age we're less likely to be able to cope with disruptions to our night-day routines, including difficulty adapting to time-zone changes, or working non-traditional hours, late at night or early in the morning.

Sleep is a critical factor in our long-term health and well being: studies show that it can play an important role in extending health and longevity and lack of sleep, in turn, can pose serious health consequences as we age.

Women face particular challenges to sleep throughout their lives. Research shows they are more likely than men to experience difficulty sleeping. Evidence also suggests that over time, sleeplessness can have a more serious impact on women's overall health than on men's. Some of the sleep challenges for women are a matter of physiology, and others can be a matter of the many roles and responsibilities that women so often take on, particularly as mothers.

• Hormonal changes throughout a woman's monthly menstrual cycle—primarily fluctuations of estrogen and progesterone—can make falling asleep and staying asleep more difficult.
• Menopause and peri-menopause bring their own set of hormone-related sleep challenges: insomnia is a common and often overlooked problem for women experiencing menopause.
• While raising young children, everyone in the family is likely to be sleep-deprived at times, but women with young children are more likely to be deprived of sleep than men.

Understanding how the aging process affects sleep can help us find better ways to treat disordered sleep. That's why this news is significant: a recent study may provide new information about why our circadian clocks may become less effective as we age.

Researchers focused on a small area of the brain responsible for regulating the body's circadian clock, which controls our sleep-wake cycle. To study the effects that aging has on the circadian clock, researchers compared young mice and middle-aged mice, looking for differences between them. What did they find?

A dramatic difference in the amount of electrical activity in the area of the brain that controls the sleep-wake cycle (circadian clock) of younger mice versus older mice.

• In the younger mice, the researchers found very active brain waves during the day, and very little electrical activity at night. In middle-aged mice, the researchers found that the brain was not as active during day, and even more interestingly, it wasn't as quiet at night.

It's as if as we age, the clock that regulates our sleeping and wakefulness ticks more and more quietly. A less effective circadian clock means less-and lower quality-sleep. The more we know about why our circadian clock deteriorates with age, the better able we'll be to develop effective treatments for age-related sleep problems.

Here's some good news: you don't need to wait for science to make new breakthroughs to improve your sleep by paying attention to the way your circadian clock works. You can reinforce your body's own circadian rhythm—and strengthen your sleep-wake cycle—by adopting these habits:

• Exercise early in the day. Morning exercise can help stimulate your mind and body to a more alert, wakeful state, and sends the get-up-and-go message to your circadian brain.
• Get outside. Exposure to sunlight stimulates the brain's SCN. Turn your coffee break into a quick walk around the block, and you'll also be helping strengthen your circadian clock.
• Routine, routine. Our minds and bodies love—and respond to—routines. Setting regular times to sleep, wake, eat, and exercise is calming to the mind and helps reinforce the body's inner circadian rhythms.

With their particular challenges to sleep, women may find paying special attention to circadian-boosting habits a natural and effective way to sleep well, no matter what number shows up on that next birthday card.

Sweet Dreams,

Michael J. Breus, PhD
The Sleep Doctor^TM