Overview

Sleep is important for you to lead a healthy and productive life. According to the American Academy of Sleep Medicine (AASM), an average adult requires seven or more hours of sleep daily for staying mentally and physically healthy. Your brain and body are busy even when you are asleep so that you can be relaxed, productive, full of energy, and healthy when you wake up from your slumber. It would be helpful for you to know about the different stages of sleep and why each one of them is important for you in achieving the magic figure of seven hours or more daily for the recommended amount of sleep.

The stages of sleep

In total there are five stages of sleep, some of them are non-rapid eye movement (NREM) sleep and some are rapid eye movement (REM) sleep. Your body cycles through all of the stages multiple times every night. On an average, each cycle lasts around 90 minutes but some cycles may last even shorter, around 50 minutes and some may last for a longer duration, around 100 minutes or more. Each cycle builds off each other and you progress from one cycle to another. Usually your sleep passes through all five stages three or four times during your entire sleep cycle.

Stages one to three fall under the non-rapid eye movement (NREM) sleep category and stage four falls under rapid eye movement (REM) sleep category.

Here’s how all stages of sleep work together.

Stage 1

In stage 1,  a person drifts from being awake to being asleep. This is a light, non-rapid eye movement sleep stage. In this stage, your sleep is shallow and not restful. During this stage, you can hear sounds and your sense of awareness is present. Stage 1 is a quick transition stage which does last for very long. In Stage 1, your mind starts to relax, your heartbeat starts to slow down, breathing starts to slow down, eye movement starts to slow down and your muscles start to relax with an occasional twitch. You may start to feel relaxed and dream, but may also feel like you are still not asleep as you transition into stage 2.

Stage 2

In stage 2, a person is still in light sleep, but drifting into a steadier sleep. In Stage 2, the sleep of a person progresses to a deeper and more relaxed sleep. Stage 2 typically lasts for 30 to 60 minutes, brain activity starts to slow down, which indicates the beginning of deep and restful sleep. In stage 2, a person is asleep but can still be easily awoken. In stage 2, breathing and heartbeat continues to slow down, your muscles start feeling relaxed, and body temperature decreases. Light sleep is very important as it makes up more than half of your sleep cycle.

Stage 3

In stage 3, a person enters into a deep sleep state. During stage 3, the brain becomes less responsive to outside stimuli, breathing and heartbeat rate slows down further and becomes regular, and muscles relax. Deep sleep is very much about the body and not mind.

Stage 4

In stage 4, a person enters the deepest sleep state. In stage 4, the body starts to rebuild and repair as tissue growth starts taking place, essential hormones are released and cellular energy is restored.  In stage 4, the brain doesn’t respond to the external stimuli. Stage 4 usually lasts for 20 to 40 minutes.

REM sleep

In the Rapid Eye Movement (REM) sleep stage, a person starts to dream, their arms and legs become temporarily paralyzed so that they don’t physically act out their dream. Typically, the first REM cycle begins about 90 minutes after a person falls asleep and recurs every 90 minutes. In the REM sleep stage, eyes move around quickly behind eyelids, and the brain becomes very active even if the body is inactive. In the REM sleep stage, breathing and heartbeat rate increases.

How much deep sleep should you get?

As per some studies, on average 13 to 23 percent of sleep is deep sleep for average adults. That means, if a person sleep on bed for 8 hours, the time spent in deep sleep is around 62 to 110 minutes. As a person starts to grow older they require less deep sleep.

Deep sleep allows the mind and body to perform the following functions:

·   Physical recovery occurs

·   Balancing out of blood sugar levels

·   Resetting of metabolism

·   Energizing the immune system

·   Detoxification of the brain

How much REM sleep should you get?

Sleep researchers believe that REM sleep is important as it allows you to process emotions and solidify some memories. So far sleep researchers have not been able to come to any conclusion on how much minimum REM sleep is good. An average healthy adult gets 20 to 25 percent sleep as REM sleep out of the total number of hours slept.

Some sleep researchers suggest that people who get a higher amount of RAM sleep may suffer from depression.

How much light sleep do you need?

Sleep researchers deem that light sleep is good for a person but they have not been able to arrive at the minimum number of time required for light sleep. Light sleep is non-rapid eye movement sleep and it is the default stage that can’t be avoided if you are asleep at all. Light sleep doesn’t sound important but it is very much part of your sleep cycle. Light sleep may not be as refreshing as deep sleep but it is a necessary stage of sleep cycle for good brain activity.

As a person starts growing older, the major part of the sleep cycle is going to be light sleep.

Conclusion

According to Sleep Standards, an average adult requires more than seven hours of sleep daily to lead a healthy and productive life. Poor sleep is going to harm your life and you may suffer from insomnia which may lead to other life-threatening diseases like cardiovascular diseases, diabetes, etc. Each stage of your sleep cycle is important.