The purpose of sleep


Why do we need rest anyway? These scientific insights reveal why it’s necessary and what happens in our bodies while we’re snoozing

The purpose of sleep

Editor’s note: Savvy mattress retailers want to do everything they can to help their customers sleep better, including offering them sound advice and tips. Feel free to share this great guidance from Better Sleep Council spokeswoman Lissa Coffey with your shoppers (with credit given, of course). The BSC is the consumer-education arm of the International Sleep Products Association.

We’re busy people. Our schedules are jam-packed with work, school, activities, sports, social events, volunteering, parenting, playing—you name it. And there’s always more to do. Whether it’s another project or opportunity we can’t pass up, we need to make time in our day to fit it all in. Unfortunately, we tend to sacrifice sleep first. We stay up later—sometimes much later—to get things done. Or we wake up earlier to get a jump on everything we need to do before the workday begins. But there’s always a price to pay. Is it worth it? Why do we really need sleep anyway?

The body tells us sleep is not an option; it’s a necessity. It regulates sleep just like it regulates eating, drinking and breathing. We can’t hold our breath for very long, and we can’t go without sleep for too long either. If we don’t eat, we can starve. If we don’t sleep, we can die. The longest anyone has gone without sleep is 11 days. But don’t try to break that record because it’s dangerous! Instead, we should follow the signals our bodies give us. When we are hungry, we need to eat. When we are tired, we need to sleep. Sleep is a natural state for us.

One way we know we are sleepy is by yawning. When we are very tired or sleep deprived, the temperature of the brain increases so it can function optimally. Yawning helps cool the temperature of the brain. The mouth opens widely and draws large amounts of air into the lungs. You may feel your chest expand, and your eyes close. Movements like these increase your heart rate and blood flow, which allows the body to cool the brain. We need to pay attention to these cues. An important function of sleep is thermoregulation, or the distribution of heat in the body so we can maintain a healthy core temperature.

Just as a delicious meal can satisfy our hunger and be enjoyable, a good night’s sleep can alleviate our sleepiness and be a wonderful experience. It’s great to wake up in the morning feeling refreshed and ready to take on the day. When we have good sleeping habits, we look forward to going to bed at night and wake up easily in the morning.

While you’re sleeping

Quality sleep helps the body conserve energy for those times when we most need energy. Research shows that energy metabolism declines during sleep, which, for example, is why we don’t need as many calories when we are sleeping as we do when we are active. Good sleep also helps the body both repair and rejuvenate. Many important restorative body functions like tissue repair, growth hormone release and muscle growth occur mostly during sleep.

Sleep also helps brain function. During waking hours, the brain produces a byproduct of the cells’ activities called adenosine. The accumulation of adenosine is one factor that makes us feel tired. After all, mental activity uses energy the same way physical activity does. Caffeine temporarily can block the actions of adenosine to artificially keep us alert, but adenosine continues to build up. The only way to clear adenosine from our system is to sleep.

Scientists also are using brain scans to show a correlation between sleep and brain plasticity. Brain plasticity, also called neuroplasticity, refers to the brain’s ability to change—for better or worse—at any age. Infants sleep from 13 to 14 hours a day; half of this time is in REM sleep, when we dream. This is significant because the brains of infants and young children are developing rapidly at those ages. Research shows similar links between sleep and brain plasticity for adults, especially regarding the ability to learn and perform tasks. A good night’s sleep helps with memory and recall. Another study shows sleep helps us deal with stress. During sleep, the brain can process an unpleasant or traumatic experience and help us recover from it. When we are stressed or have an illness, we usually need more sleep. The body and mind need rest, so sleep is good medicine.

The purpose of sleep

Too much, too little

On the flip side, it’s possible to get too much sleep, which also can be harmful to the body. Oversleeping—more than nine hours of sleep a night for an average healthy adult—has been linked to medical problems such as diabetes, obesity and heart disease. Researchers also note depression is associated with oversleeping. Further, people of lower socioeconomic status may have less access to health care and be more likely to have an undiagnosed illness that causes oversleeping.

Hypersomnia is a medical condition marked by a constant sleepiness that isn’t relieved by long hours of sleep at night or napping during the day. Anxiety, low energy and memory problems often accompany hypersomnia. Sleep apnea is a medical disorder that interrupts the normal sleep cycle. People with this condition stop breathing momentarily during sleep, which can lead to an increased need for sleep. Consult with a doctor if you have any of these symptoms.

Just right

As you can see, too much sleep is just as bad for us as too little sleep. Everyone’s sleep needs are different, and ideally, we want to find that Goldilocks formula when the amount of sleep we get is “just right.”

A mattress is the foundation of a good night’s sleep, so when you are choosing a mattress, make sure you find one that is just right for you. With so many options on the market today, this is not a difficult task. Rest-test mattresses in a store by lying down on them, just as Goldilocks did. Getting horizontal is the best way to get a real feel for what it will be like for you when you are sleeping.

If you find yourself dozing off at the mattress store, that’s a good indication that you need more sleep—and that the mattress is a good match for you!


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Lissa Coffey is a relationship expert, author of several books and broadcast journalist. A spokeswoman for the Better Sleep Council, she stars in several videos that offer sleep and mattress-shopping tips for consumers.


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