An average person lives 27,375 days, and one-third of that is actually spent sleeping. Considering how much we sleep, it is surprising that the reason why we sleep, its importance, and most of the things we know about it have only been discovered in the last 30 years. 

Sleep is incredibly mysterious that every year of study, we learn new things about it. Our knowledge about it has advanced throughout the years, but there’s still so much more to learn. 

Here are seven incredible facts about sleep that you should know. 

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1. Half of the population sleep with their eyes open

According to the National Library of Medicine study, up to 50% of the population may have a condition called nocturnal lagophthalmos. This condition prevents the eyelids from fully closing during sleep. 

When you sleep with your eyelids just partially closed, your eyes are exposed to the open atmosphere. Since eyelids function to lubricate the eyes, people with this condition have their eyes dry out significantly in their sleep. 

The treatment for this usually involves artificial tear eye drops several times per day along with eye gels at bedtime. An eye mask worn during sleep may also help keep the eyelids closed. 

2. Sleep deprivation leads to weight gain

Sleep deprivation raises the production of the hunger hormone called ghrelin and lowers the hormone levels that make you feel sated, called leptin. The result? This imbalance caused by not getting enough sleep leads to increased appetite during the day.

Over the years, sleep science has shown that there is a strong link between sleep and eating. Sugar can interfere with sleep quality, just as sleep interferes with appetite. Having a flexible diet with the right balance of meat and veggies can aid your sleep, and having a good night’s sleep will help regulate your eating hormones. 

3. You can have too much sleep

We often focus on the dangers of having too little sleep, but sleeping too much also has some risks.

Experts from the National Sleep Foundation say that somewhere in the range of seven to nine hours of sleep is standard for most adults between 18 to 64 years old. 

The “right” amount of sleep varies as some people will feel great on seven hours of sleep while others need more. However, regularly sleeping more than eleven hours a night is considered excessive.

Oversleeping has been linked to health and performance problems, including depression and cardiovascular diseases. 

4. You burn calories in your sleep

When you think of ways to burn calories, sleep often does not come to mind. But even in our sleep, our body requires a constant energy source for brain activity and other essential body functions. 

Sleep is not a passive activity, so burning calories during sleep is undoubtedly necessary to sustain breathing, blood circulation, temperature regulation, and the growth and repair of muscles and organs—this is called the basal metabolic rate. 

Another fun fact is sleeping in a colder room forces the body to burn more calories to keep you warm. 

5. You need four nights to make up for an hour of lost sleep

It is no longer uncommon for people to have less than six hours of sleep. But, unfortunately, losing sleep is ever common these days, especially for people who work in the medical field or other shifting jobs. 

Sleep deficit is cumulative but doesn’t always mean that we feel tired. Research shows that we can cognitively adapt to chronic sleep restriction, which means we do not feel particularly sleepy even with incomplete sleep. However, it will show a significant decline in our body’s physical and mental performance. 

It may seem like sacrificing sleep to study or work for a few more hours helps you get things done more, but getting sufficient sleep actually improves cognitive performance, which will then result in you being more focused and efficient throughout the day. 

When you are sleep-deprived, you may feel better after getting a little extra rest, but the snowballing effect of sleep loss is a debt that is hard to repay. If you are hoping to catch up on some sleep, you can try to increase your sleep time slowly by 15 to 30 minutes a night until you reach the optimal amount of sleep for your body. 

Understanding how much our bodies need sleep is the first step in prioritizing it as one of the most important ways to take charge of our well-being. 

There is still so much to learn about sleep. While it is still unlikely to know everything about it, continually learning about sleep can significantly improve the quality of our life.

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