The Importance of a Good Night’s Sleep
A good night’s sleep helps your brain and body grow, heal, and rejuvenate. It also protects your memory and allows you to solve problems, pay attention and concentrate, and control emotions. But despite these benefits, millions of people are not getting enough sleep. Lack of sleep may lead to depression, weight gain, high blood pressure, diabetes, and a host of other health problems. A growing body of research suggests that adequate amounts of restful slumber are essential to physical and mental well-being.
Scientists know that during sleep, your body produces a series of critical biochemical and metabolic changes that promote healing and rejuvenation. But the reason for these vital changes remains a mystery. One theory is that sleep serves to conserve energy by allowing you to reduce activity and arousal levels for an extended period of time. Another is that it provides a way to clear the brain of waste products, which would otherwise build up and cause inflammation. Still others suggest that sleep enables us to learn and retain information by converting short-term memories into long-term ones, while erasing unneeded data.
What is known is that a good night’s sleep is not only necessary for physical and mental well-being, but it is also a very complex and variable phenomenon that occurs in several stages. It starts with light non-REM (non-rapid eye movement) sleep, then progresses through two other non-REM phases before moving into REM sleep. Normally, it takes 1.5 to 2 hours for the brain and body to complete a sleep cycle.
The need for sleep has been documented by many cultures throughout history. But it was only in the 1940s that a physician named David Dingerdissen, MD, established that the human body needs a period of recurrent non-arousal each day. His work led to the discovery that the absence of this recurrent pattern results in death within weeks. In the decades since, researchers have determined that all mammals and most birds, reptiles and insects exhibit sleep-like behavior.
In humans, the natural sleep-wake cycle, which is influenced by environmental cues such as the sun setting and rising, usually results in six or seven periods of waking and sleeping each day that alternate with one another. As people age, this alternation shifts toward monophasic sleep with an increasing concentration of nocturnal sleep.
In addition to regulating the body’s hormone production, the sleep-wake cycle influences how much your eyes and ears open and close, the temperature you experience, and the speed at which your heart beats. It also affects the amount of energy you use while at rest, and whether or not you have dreams. Dreams are most common during REM sleep, but they can occur in other stages of the sleep cycle as well. Occasionally, a person will have a frightening dream, which is called a nightmare, during a deep non-REM sleep stage. These nightmares can be dangerous and should never be ignored. The underlying causes are not fully understood, but researchers are beginning to understand more about the mechanisms that create and trigger them.