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What Happens to Your Body When You Sleep?

Although you are not aware of your body when asleep, it carries out some vital processes that are designed to help keep you fit and healthy. This is why a good night’s sleep is vital.

Here are some of the processes that happen to different parts of your body as you sleep:

The brain

While you sleep, cerebral fluid is pumped through your brain; this fluid washes away waste products produced by the brain cells.

Yes, as you sleep, you are literally being brainwashed.


During sleep, your breathing slows down to a regular rhythm. This is the opposite of exercise when your lungs work harder and faster.


Growth hormones are released during sleep and these rebuild muscles and joints. If you are an athlete then long sleep is vital to replace torn tissue and damaged muscles caused by competing and hard training.


As you sleep your heart rate goes down. This also means that your blood pressure drops. During rapid eye movement (REM) sleep if you have a hectic dream such as being chased, or falling down, then your heart rate temporarily may speed up, then slow down again as you enter another cycle of deep sleep.


If you have eaten shortly before going to sleep, then your stomach will be working to digest your food. If your meal was heavy in carbohydrates then the chemical tryptophan will be produced in the stomach and this can cause you to wake up. It is best to avoid large meals near bedtime.


Several times during the sleep cycle you will enter REM sleep when your eyes move rapidly even though they are closed and not seeing.

Immune system

During sleep, the body produces proteins including ones that aid the fight against infection. Research has shown that the immune system is more active when asleep, which means that sleeping a lot when ill will help the recovery process.

Body temperature

The body temperature drops when you sleep as adrenaline levels dip. Sometimes the body tries to compensate for this loss of temperature by perspiring which is why some people wake up in the night feeling sweaty.

Sleep is needed for the body to function well. Lack of sleep means that the body cannot perform its necessary maintenance routines and this can have a detrimental effect on health.

Sleep in comfort