Getting enough restful sleep is not a basic luxury, it is a biologic necessity. Sleep is far more than about giving the body some rest. It is the time when our brains re-pattern and our brain cells form new connections. In other words, sleep is necessary for learning and maintaining our memory. Sleep deprivation not only compromises our performance but increases our likelihood of errors and forgetfulness. Our memories appear to be restructured and reorganized during sleep. During sleep some synaptic connections between nerve cells seem to weaken while others grow stronger. New information (learning) is incorporated and stored in the revised or updated neuron network.

As a result of this sleep physiology and the re-patterning of synapses during sleep we can see that the needs for sleep might be linked to the quantity of learning achieved when we were awake. Decreased cognitive stimulation as we age may seem to compromise our sleep. The more we stimulate our intellect when awake, the better we sleep, and the better we sleep the more we remember and the better we learn.

The typical sleep cycle involves 10 to 20 minutes of drowsiness and very light sleep. This is followed by an hour or so of very deep sleep, followed by a rapid eye movement (REM) period when we dream. During a night the cycle repeats, with the length of deep sleep decreasing and REM sleep increasing.

The most important age related changes in sleep include a decreased continuity of sleep with an increase in the number of arousals during sleep; a tendency for the major period of sleep to occur earlier in the night; a tendency for REM sleep to occur earlier in the night; a decrease or loss of the deepest parts of non-REM (NREM) sleep; increased napping and a tendency to spend more time in bed. This type of sleeping pattern with a period of deep sleep followed by more frequent arousals may have been important for our ancestors because lighter sleepers might have been more sensitive to environmental factors such as nocturnal animals.

Studies of sleep in healthy elderly people also suggest some gender differences: elderly men show poorer sleep maintenance than women. But women are more likely than men to complain of sleep problems and to take sleeping pills, possibly because they are more likely to share their concerns, or perhaps they are more sensitive to sleep quality and sleep loss than older men.

Diseases such as depression, dementia, and sleep disordered breathing produce characteristic changes in the way we sleep. In depression there is a shortened time between the onset of sleep and REM sleep, various changes in brainwave patterns and early morning awakening. Sleep in patients with Alzheimer’s disease can have a disrupted sleep-wake cycle that worsens as the disease progresses. There can be longer napping, decreased eye movements in the REM period and increases in breathing problems during sleep. Sleep apnea is a common problem as we age. While there are several causes, the major effect is relaxation of the throat muscles and tongue during sleep that closes off airflow through the nose and throat. People with sleep apnea typically snore loudly, and their breathing periodically stops during sleep. They may be completely unaware of the problem although if they have a partner the partner is certainly aware. It is an important condition that usually responds to medical therapy but untreated can increase the risk of heart attack and stroke.

Two basic factors govern the nature of our sleepiness and the quality of our sleep: the body’s circadian rhythm and the amount of time we have been awake, called the homeostatic regulation. The interaction of these two factors determines the best time for us to sleep. While it may sound like a tautology and overly simplistic, the key to good sleep is to sleep when you are sleepy, as produced by your body’s natural rhythms. The trick is to fit the sleepiness within the demands of modern life.

The body’s internal clocks were called circadian (about a day) rhythms in 1959 by Dr. Franz Halberg, a pioneering scientist who founded the science of chronobiology. Our normal circadian rhythm runs on a 25-hour cycle and the challenge is either to flow with the normal cycle, which socially becomes challenging, or try to reset it into a 24-hour cycle using techniques like bright morning light and exercise. If we try to sleep too early within our natural cycle we will experience insomnia. The solution is to wait until we feel sleepy, often an hour or two later, because these powerful biological rhythms are almost impossible to fight. This means that Benjamin Franklin’s aphorism “Early to bed, early to rise, makes a man healthy, wealthy and wise” is only half true. The “sleep is more valuable before midnight” maxim is also a myth. We need to sleep when our natural rhythms tell us to. Sleeping pills really do not solve the problem and are best used for very specific short-term circumstances like being hospitalized.

What about napping?

A normal feature of the circadian sleep cycle is to feel slightly sleepy right after lunchtime. Not everyone feels this temporary fading in alertness, especially if over caffeinated or working in a stressful setting. This sleepiness can be increased with a high carbohydrate meal and/or a weak alcoholic beverage such as one beer or a glass of wine. So a short “siesta” of 20 to 30 minutes can be refreshing, does not disrupt our normal sleep cycle and is dense in NREM sleep. A longer nap or napping later in the afternoon may fragment the sleep-wake cycle, worsen insomnia and produce a sense of fuzziness and disorientation on arising.

Things that can help produce and maintain normal sleep

Exercise can significantly help us to sleep more restfully. However, the timing of exercise is important and should not occur within three hours of sleep. The reason for this is that exercise increases your body temperature, awareness and alertness. Exercise also helps to modify (entrain in psychological parlance) the sleep cycle. For example, early morning exercise in sunlight will help you to sleep better in the evening. Limit alcohol at least three hours before bedtime. Alcohol reduces the amount of deep sleep and REM sleep, increases the awakenings and further fragments sleep. In addition, alcohol can exacerbate any symptoms of obstructive sleep apnea. Also avoid caffeinated beverages and foods except right after you awaken. Sex at bedtime with your loving partner is a pleasurable aid to restful sleep. Obviously it can be disruptive to sleep in some passionate circumstances.

If after 30 minutes you find yourself tossing and turning and unable to get to sleep, get up and do some non-stimulating activity. Wait until you feel sleepy to get back in synch with your circadian rhythms, then go back to bed.

“Sorrow can be alleviated by good sleep, a bath, and a glass of wine.”
—Thomas Aquinas

Mark E. Williams, MDThe Art and Science of Aging Well

How Aging Affects Our Sleep