Why Do We Need Sleep?

Everyone knows that they feel better, both mentally and physically, after a good night’s sleep. But scientists are only just beginning to understand the vast extent of its benefits, and why we need it. Sleep does more than give your brain and body a lift—it repairs them on a cellular level, strengthening key systems that help us fight disease, improve fitness, and look and feel healthier.

The need for sleep is biologically driven, based on the body’s internal clock and natural rhythms. It’s a lot like our bodies’ circadian rhythms, which govern things like growth, reproduction, and aging. These rhythms operate on a daily time scale, and signal the drive for sleepiness at certain times of day. The need for sleep also increases when we’re stressed, ill, or engaged in mental or physical activity that taxes our bodies.

During sleep, your body goes through several stages of sleep, with each stage characterized by specific patterns of brain waves and muscle activity. Scientists now know that sleep is not simply a passive state of inactivity, but a highly active process during which the brain processes events from the day and replenishes energy resources.

In addition, during slumber, your muscles repair themselves, your memory is cleared out, and hormones are released that affect everything from blood pressure to hunger levels. Many diseases — including heart disease, diabetes, high blood pressure, and depression — are associated with sleep problems. In fact, many of the treatments for these diseases involve getting more sleep.

Fortunately, you can get more of the restful sleep you need by maintaining a regular sleep schedule, going to bed and waking up at the same times each day, relaxing before bed (such as through a bath or reading), and avoiding bright lights or electronics around your bedtime. These activities can “train” your brain to expect sleep, making it easier for you to fall asleep and stay asleep. If you have trouble sleeping, talk to your doctor or nurse. You may need testing or treatment for a sleep disorder.