Staying up late will be detrimental to human health, because the adrenal cortex hormone and growth hormone are all secreted during the night when people are sleeping. The former is secreted before dawn, which can promote the metabolism of carbohydrate in human body, and protect the development of muscle; while the latter is produced only after sleep, which can not only promote the growth and development of young people, but also can delay the aging process of the elderly. As a result, staying up late will cause a variety of harms to human body.
First, frequent fatigue and decreased immunity
The most serious sequence caused by staying up late is fatigue and lack of energy. What's more, the immunity of human body will decrease accordingly. And some other symptoms such as cold, gastrointestinal infections, allergies will also appear.
Second, headache
The next day after staying up late, you will suffer from headache when you are at work or at class. You will be unable to concentrate. What's more, long-term staying up late and insomnia will also bring invisible damage to our memory.
Third, dark circles and puffiness
Night is the time for human body to have a good rest. Without adequate rest, you will feel extremely tired, which will lead to poor blood circulation around the eyes, causing dark circles or blood streak in the white of the eye.

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