TL;DR Science: Sleep

By Erin Kang
September 02, 2020 · 5 minute read


Cognitive Science


Sleep. Everybody knows it’s an important part of staying healthy, but most people don’t know why. The act of sleeping is much more complex than most people realize and this article will break down some of the main phases of sleep as well as some of the benefits getting a good night’s rest can give you.


What is Sleep?

Although we spend almost one third of our lives asleep, scientists have yet to discover the function of sleep. However, over the past few years, researchers have made great strides in recognizing that sleep consists of multiple different stages.

There are two overarching stages: rapid-eye movement (REM) sleep and non-REM sleep. Non-REM sleep can be split into three different stage:

Stage 1 non-REM sleep is the turning point between wakefulness and sleep. This stage only lasts for a few minutes (about 5 to 10 minutes) and is also the period where your heartbeat, breathing, and eye movements begin to slow down and your brain waves slow down from all the chaos of the day.

Stage 2 non-REM sleep is the transition from light sleep to deep sleep. Your heartbeat, breathing, and muscles relax even further. Your body temperature decreases and any eye movement comes to a stop.

Stage 3 non-REM sleep is needed in order for you to feel refreshed in the morning. In this period, the body repairs itself and strengthens the immune system. The older you get, the less deep sleep you get. However, it is said that you still need as much sleep as when you were younger.

Stage 4 REM Sleep happens about 90 minutes after you fall asleep. The brain activity seen during REM sleep is almost identical to that seen in wakefulness. REM sleep is often characterized by rapid eye movement and a rapid increase in heart rate and blood pressure. Most of your dreams occur during REM sleep, but your arm and leg muscles are temporarily paralyzed. This prevents you from acting out your dreams and potentially injuring yourself. 

Why is Sleep So Important?

Despite the considerable amount of grey area we have yet to explore, researchers do know that sleep plays a crucial role in your health and vitality. Getting the right amount of quality sleep at the right time is one of the most important steps in protecting and improving both your mental and physical health. Sleep is involved in healing your heart and blood vessels and supports healthy growing and development. You can think of sleep as sort of like the process of revitalizing the mind and soul; starting off with a fresh, clean slate each time you wake up from a good night’s sleep. I’m sure most of you have pulled an all-nighter before, in fact, I’m guilty of pulling a few myself. However, as most of your hormones and bodily systems depend on sleep to restore and maintain your good health, it is imperative that you get the suggested amount of sleep (8 hours). 

 If you would like to learn more about the science behind sleep, check out this Ted Talk with sleep scientist, Matt Walker:

If you’re sleep deprived, you may notice a decrease in psychomotor and cognitive speed, trouble making decisions, and controlling your behavior and emotions. Children and teenagers, especially, are prone to mood swings, may feel depressed, and lack motivation with lack of sleep. Furthermore, sleep deficiency leads to an increased risk of heart disease, kidney disease, high blood pressure, diabetes, stroke, and obesity. So why exactly does sleep deficiency cause so much suffering? Well, researchers believe that when we are awake, we use up our energy sources, which get broken down into byproducts. One byproduct, adenosine, accumulates in the body and increases the urge to sleep. Other waste products from the breakdown of energy sources continue to build up in the brain and unless we clear those products away when we sleep, the accumulation will lead to the negative effects of sleep deprivation.

Sleep Disorders

Over 60 million adults in the US suffer from a sleep disorder, making it difficult to get sleep on any given night. The most common sleep disorder is insomnia. Someone with insomnia will have a hard time falling or staying asleep. Different types of medications and counseling can help relieve insomnia and allow for the person to re-establish a normal sleep schedule. Another common sleep disorder is sleep apnea. Sleep apnea is a breathing disorder that causes your breathing to stop. These pauses can vary anywhere from a few seconds to minutes and can occur 30 or more times an hour. The pauses completely disrupt a normal sleep schedule and people with this disorder have a higher risk for accidents and other medical problems. The cause of sleep apnea differs from person to person. You are more at risk for sleep apnea if you are overweight, male, or have small airways. Conditions such as heart disease, nerve disorders, and lung disease, as well as mental illnesses, including depression and anxiety can all be possible causes that lead to sleep disorders. A novel study regarding the neurotransmitters, gamma aminobutyric acid (GABA) and glycine found that identifying the neurotransmitters involved in sleep paralysis could help researchers molecularly target possible ways of treating sleep related disorders, such as narcolepsy and REM sleep behavior disorder.


Sleep continues to be one of the most researched areas of science, especially since our quality of life depends so strongly on it. However, it remains one of the greatest mysteries of the scientific world. In any case, if there’s one thing you should take away from this article, it’s that missing a night’s sleep can have more severe consequences than simply feeling tired. Make sure to turn off your TV, set that alarm clock, and head to bed early to keep your body rested and your mind fresh for the days to come!


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