There’s nothing quite like waking up refreshed after a good night’s sleep. During slumber, the body is hard at work, repairing muscles and sweeping away waste. It also releases hormones that affect everything from hunger to stress levels. And researchers have recently discovered that sleep may be important for boosting the immune system.
The study of sleep is called “sleep science.” It’s been around for hundreds of years, but only in the last few decades has there been a real revolution in the field. This can be traced back to the discovery of a stage of sleep, usually described as rapid eye movement (REM) sleep, which has characteristics very different from those of non-REM (NREM) sleep. REM sleep is often considered the “paradoxical sleep” because its characteristics are so unlike those of normal sleeping.
A number of physiological observations have been regarded as signs of sleep, including a characteristic horizontal posture in many animals, the absence of overt goal-directed behavior, and a particular EEG pattern. These criteria are generally satisfied during sleep, but can occasionally be violated in states that are clearly behaviorally active (as in sleepwalking), or even during hypnotic trances. Despite these limitations, the convergence of several behavioral and physiological criteria makes sleep a fairly reliable phenomenon to distinguish from other behaviors.
During the sleep cycle, the body goes through four stages. The first three are called non-rapid eye movement (NREM) sleep, and the final phase is characterized by a period of dreaming, called rapid eye movement or REM sleep. Each of these phases involves a progression into deeper sleep. In humans, a typical sleep cycle takes about six to nine hours.
In addition to providing the body with an opportunity to repair itself, sleep is important for helping people concentrate, think abstractly and solve problems. This is a key reason why students who regularly miss out on sleep tend to get poor grades in school. Studies have also shown that lack of sleep makes people more likely to become obese, depressed and ill.
It’s no wonder that research is showing that getting a full night of sleep can be just as important for overall health as diet, exercise and smoking cessation. In fact, the American Heart Association has included adequate sleep as one of its “Life’s Simple 7,” along with healthy eating, moderate drinking, weight control, physical activity and not smoking.
Although a good night’s rest is essential for mental and physical well-being, it can be elusive. Insufficient sleep can lead to a variety of health problems, from fatigue and irritability to depression and anxiety. Fortunately, by following a few easy tips — such as going to bed at the same time each night and avoiding caffeine — you can help ensure that you’re getting enough high-quality sleep for optimal health.