Healthy sleep is central to overall good health, yet far too many of us take it for granted. Busy with other challenges to good living, we shortchange the number of hours we allot each day to slumber. We fail to provide ourselves with comfortable beds, darkened rooms, and the quiet that facilitates sound sleep.
And we pay the cost, with some items on the bill quite unexpected. For example, some sleep research suggests that inadequate healthy sleep can lead to weight gain and is a factor in the national obesity crisis. Lack of sleep muddies clarity of thought. The sleep stage known as REM (rapid eye movement) sleep is believed to play a role in the mental processing of the experiences of the day just past and the organization of memory. With too little REM sleep, memory may suffer. If prolonged, inadequate healthy sleep may be a precursor to cardiovascular disease. And even in the short term, the sleep deficit that results from too little sleep leads inexorably to daytime drowsiness, a potential killer to anyone operating heavy machinery or driving an automobile.
In 1910, the average adult American slept nine hours a night. Since then the average has dropped steadily. Most sleep physicians believe that the average adult needs eight to eight-and-a-half hours of sleep a night, with seven hours being the minimum for almost everyone. Nonetheless, surveying by the Centers for Disease Control shows that the percentage of Americans between 25 and 64 who sleep six hours or less a night increased from 20 to 25 percent in 1985 to 30 percent in 2004.
Sleep studies show that sleepers cycle through a variety of phases as the night goes on: light non-REM sleep, deep non-REM sleep, light non-REM sleep, and roughly 90 minutes after first falling asleep, the first round of REM sleep, which may last 15 minutes. During REM sleep most dreaming occurs and the legs and arms are temporarily paralyzed, perhaps to prevent sleepers from acting out their dreams. But then the cycle recurs, first non-REM sleep, light and deep and light, followed by another, somewhat longer round of REM sleep. The phases of deep non-REM sleep, when blood pressure drops, the heart rate slows, and body temperature is lowest, are believed to be the most refreshing and restorative periods of sleep. They are also the times when the sleeper is most difficult to awaken.
Typically the longest phase of REM sleep, and the most dreaming, occurs shortly before morning during at the end of the fifth sleep cycle of the night. In adults, about three-fifths of a night’s sleep is light non-REM sleep, one-fifth is deep non-REM sleep, and one-fifth is REM sleep. Infants and children require much more sleep than adults and much more of their sleeping time is devoted to REM sleep.
Whether sleep is healthy or not is at least partly within the sleeper’s control. Check your own bedroom performance against the 10 Commandments of Sleep. If you fall short, reflect on how you might modify your behavior so that you can better adhere to these norms. Your sleep health may also be adversely affected by a variety of sleep disorders, many of which are treatable if diagnosed.
This web site offers a wealth of information about sleep apnea and many other sleep disorders. If you believe you may have a sleep disorder, you should consult your personal physician or a doctor who specializes in sleep medicine. Before you arrange a professional consultation, however, download a copy of the American Academy of Sleep Medicine sleep diary and keep it for two weeks. This will provide you (and your doctor) specific information about your sleep patterns.