Why Is Sleep So Important to Humans?

For decades, scientists have tried to understand the complex function of sleep. Without sleep, mammals die, so it’s crucial to survival. But the reasons are a bit of a mystery, though one theory says that sleeping lets us save energy for activities during the day by stockpiling resources and slowing down activities that use lots of energy. Another possibility is that sleep helps clear toxins from our brains.

A good night’s rest also strengthens memories and emotional stability. And it may help our bodies heal and repair tissues that were worked hard during the day. Getting the right amount of sleep, or “sleep hygiene,” is important for staying healthy and performing well at work or school. It’s a good idea to create a bedtime routine that includes relaxing activities, and to maintain a regular schedule of going to sleep and awakening each day.

But getting enough sleep isn’t easy. It’s affected by many factors, including stressors like work or relationships, financial pressures and health concerns. Over time, chronically poor sleep can lead to obesity, a weakened immune system and a higher risk of heart disease, high blood pressure and diabetes. It can also lead to accidents, depression and a greater likelihood of mental illness.

Research shows that adults need 7 or more hours of sleep a night to feel alert and energized throughout the day. But sleep is often disrupted by things such as stimulants, alcohol or caffeine, some medications, irregular shift work and a lack of exercise or relaxation at bedtime. People who have sleep disorders, such as insomnia or snoring, are especially prone to not getting enough rest.

Modern medicine’s understanding of sleep is like a partially assembled jigsaw puzzle. Researchers know what some of the pieces look like and have a rough idea about how they fit together. But they don’t fully understand why it is essential to humans.

The answer to that question likely lies in many different parts of the body and brain. In babies, children and teens, a lot of important growth and development occurs during sleep. In adults, it is linked to a healthier immune system and lower risk of certain diseases, better thinking and reaction times, and less weight gain and a lower risk of diabetes. It also boosts our mood, which can have a positive effect on relationships and workplace performance. Sleep deficiency can lead to a wide range of negative consequences over time, from memory loss and poor judgement to depression and anxiety. Sleep also supports cardiovascular health and keeps our hearts working at a normal pace. But many Americans are not getting enough of the rest they need to be healthy and productive. The reasons for this are complex, and can include social or cultural barriers to getting health care and dealing with a mental illness. They can also include a lack of insurance coverage, or difficulty navigating health care systems and finding a doctor who can treat a sleep disorder.