The Importance of Sleep
For decades, sleep was considered a passive activity that caused the body and brain to shut down. But researchers now know that a variety of active processes take place during slumber—processes that are critical to mental, physical and emotional health. For example, when you’re asleep, your muscles repair themselves, your brain sweeps out waste and new memories are formed. Sleep also contributes to how well your immune system functions and helps you think clearly. Sleep deprivation is linked to obesity, heart disease and depression. Sleep is so important that it’s one of the seven basic pillars of good health—along with exercise, diet and stress management.
The reasons why humans need sleep remain a mystery, but researchers have a few theories. One is that sleeping in a single block at night allowed early humans to conserve energy, avoid predators and meet their need for rest. Another is that the circadian rhythms that keep us in tune with nature’s 24-hour day-night cycle work together with a natural sleep drive (a desire to go to bed that increases in intensity the longer you are awake) to help ensure we get enough sleep.
A third theory is that we evolved to sleep in long stretches at night so we could save energy for hunting or gathering food. And lastly, some experts believe that sleep enables the mind and body to process and consolidate information, as well as to rest and heal.
Most people need at least 7 hours of sleep a night to feel rested. People who regularly get less sleep tend to be heavier and have a higher risk of obesity, heart disease, high blood pressure and diabetes. They are also more likely to experience mood disorders like anxiety and depression.
Getting a good night’s sleep starts with a healthy lifestyle. The best way to ensure you’re getting enough sleep is to make it a priority and create a regular routine, going to bed and waking up at the same time each day, including weekends. Other tips include limiting your screen time before bed and avoiding caffeine, alcohol and nicotine before you sleep.
In 1983, a researcher named David Rechtschaffen made an important discovery: without a significant amount of sleep, rats will die. He was motivated to explore why mammals and other animals spend so much of their lives unconscious, unable to hunt for food, protect themselves from predators or reproduce.
It turns out that all mammals, birds and reptiles sleep. They do so in a variety of ways, from snoozing on the ground to sleeping while they’re moving and even dreaming. But it wasn’t until the development of electroencephalogram (EEG) technology that scientists were able to study the brain and body during sleep.
Research has found that the body goes through four or five cycles of sleep in a night, ranging from light to deep to REM. During the REM cycle, the eyes move rapidly, brain waves are similar to those during wakefulness and you’re likely to be dreaming. It’s during this stage that the brain releases growth hormone and repairs the body’s tissues and cells.