On average, humans are asleep for about a third of their life. Sounds like a waste of time? On the contrary! You might not realize it, but your body is actually hard at work while you're off in dreamland.
Deep sleep and Rapid Eye Movement, or REM, sleep phases alternate every 90 minutes or so. During deep sleep, our body works like a computer running updates in the background. It produces growth hormones for regeneration and activates the immune system, so that defense cells can fight off viruses and bacteria. That's why they tell you to "sleep off" that bug!
During REM sleep, our brain is processing the day's events and is freeing up short-term storage space for the next day. This is when you dream! But you don't just experience alternate versions of encounters you had over the last 24 hours in your subconscious. Dreams can also be bizarre and completely unrelated to your personal life. When you're riding unicorns or chasing someone down as a private investigator in your dreams, that's your brain's way of training areas that would otherwise go unused.
Without sleep, both our body and our brain would lack sorely needed working hours.
… and how much sleep do we need?
That depends on your age. The American National Sleep Foundation recommends 14 to 17 hours of sleep for a newborn baby (though the little ones are highly unlikely to sleep for 14 uninterrupted hours, as sleep-deprived new parents will be able to tell you).
Elementary school children should sleep nine to 11 hours, and grown-ups should get seven to nine hours of shut-eye a night. These are merely recommendations, of course; the actual amount varies from person to person. But adults should definitely not dip below six hours a night. On the other end of the scale, some don't feel awake without ten hours of sleep.
Too much of a good thing can be harmful, too. If you need more than ten hours of zzz to feel somewhat alive, your sleep quality may be lacking. And researchers at Cambridge University found out that sleeping more than eight hours a night is associated with a greater risk of stroke.
What happens when you don't sleep at all?
Volunteers in science experiments have stayed awake for up to ten days at a time. But sleep deprivation is a method of torture for a reason.
The longer the body stays without sleep, the more problems you will have to deal with: sinking body temperature, declining concentration, apathy and a partial or total loss of cognitive and motor abilities. In the second consecutive night without sleep, reaction time and body control plummet to the level of someone with a blood alcohol of 0.85 per mill.
Researchers are split on the question of whether severe lack of sleep could actually kill you. It depends on how you interpret the cause of death. With fatal familial insomnia for example, patients die after six to 30 months with practically no sleep. But the direct cause of death in these cases is multiple organ failure.
What's keeping us from sleep?
Many people know, but only few stick to it: smartphones should be turned off as early in the evening as possible – and you should never take your devices to bed with you!
The blue light coming from the screen is pretty much the opposite of sleep-inducing. Our eyes tell the brain that it needs to stay awake. That's why less melatonin is produced –the hormone in charge of our circadian rhythm, significantly contributing to restful sleep.
In addition, our minds are running on high when we're writing emails or updating our social media profiles. And active minds take longer to fall asleep.
Other no-gos for a good night's sleep include alcohol and caffeine. The rule of thumb is to have the last coffee of the day no later than six hours before you go to bed. Too much noise and light in your bedroom are also factors that can keep you from sleeping.
How to sleep well
We already covered the "no phones in bed"-rule. In addition to that, you should keep the division between different areas in your apartment intact, if space permits. Work in the office, watch TV in the living-room, et cetera. This way, you'll associate the bedroom with sleeping and rest.
People who always go to bed at the same time, including on the weekends, have an easier time falling asleep. Pillows and matrasses should support your head and body in all the right places.
All of that and a quiet, dark bedroom with a temperature between 59 and 64 degrees Fahrenheit make for perfect conditions for a nice, deep sleep. Have a good night!