Sleep is a time for the body to make self-adjustments, in which all the body's functions are transformed and renewed. With the accelerated pace of society, people's lifestyles have changed a lot, and sleeping late has become the norm for many people, especially young people, who go to bed at one or two o'clock in the morning. However, sleeping late not only affects the next day's normal study and work, more seriously, it will destroy the body's normal metabolic function, bringing great health risks. Long-term late to bed in the end how much harm to the body? Come on, let's feel it together.

　　What are the dangers of sleeping late?

　　▶ Memory loss

　　The brain will produce a lot of metabolic waste due to the high energy consumption of brain cells when working, and the brain will switch to "clean-up mode" when sleeping. However, if you have been staying up late and feeling sleepy after work, it is likely that the metabolic waste in the brain is gathered too much, so that people will become slow to react, depressed or irritable, reduced efficiency, gathered to a certain extent and even kill the brain cells, causing damage to the brain, but also neurasthenia, insomnia and other problems, and in severe cases, it may lead to vascular origin of dementia and other diseases.

　　▶ Vision loss

　　Stay up late when the most tired organ is the eyes, often stay up late may induce central retinitis, resulting in a sudden drop in vision. Even staying up late for a long time may result in blurred vision, shadows in the field of vision, or changes in the colour of sight. Most patients' vision can be restored to a better level without treatment, but the recurrence rate is very high, and vision can be permanently damaged after several episodes.

　　▶ Deafness and tinnitus

　　Lack of sleep tends to cause insufficient blood supply to the inner ear, harming hearing, and prolonged late nights may lead to deafness.

　　▶Damaged skin

　　Staying up late for a long time can do a lot of damage to your skin, and it's not an exaggeration to say that it makes you older and uglier. 10 p.m. to 2 a.m. is the time when the skin's metabolism is at its peak, and if the body is sleeping peacefully, the skin can handle metabolic waste with ease. If you are staying up late, your endocrine and nervous systems will be out of whack, making your skin dry, less elastic, dull, and giving rise to problems such as acne, pimples, and dark spots. Staying up late can also lead to endocrine disorders, causing hair loss and can also cause baldness.

　　▶ Increase gastrointestinal crisis

　　The stomach is a more sensitive organ in the body, and the epithelial cells of the human gastric mucosa have to be renewed once in an average of 2~3 days, and usually at night. If you eat at night, the stomach and intestines do not get rest, which will affect their repair process. At the same time, the night snacks for a long time stagnation in the stomach, prompting a large number of gastric juice secretion, the gastric mucosa caused by stimulation, over time, easy to lead to gastric mucosal erosion, ulcers. At the same time, in the late night smoking, drinking strong tea, coffee on the gastric mucosa also has a bad stimulation.

　　▶ Decreased immunity

　　Often stay up late, persistent fatigue, mental instability, the body's immune system will follow the decline. Night is the peak time of the body's production of new cells, stay up late so that the body continues to be in a state of consumption, the immune system to resist external influences, repair the body's tissues to double the work. According to the survey, adults as long as three nights can not guarantee 7 to 8 hours of sleep, immunity may be reduced by 60%.

　　▶ Increase the chance of heart disease and the risk of sudden death

　　Long-term "black and white" people, not only the temper will be bad, the internal organs can not be adjusted in a timely manner, so that the chances of heart disease increased. Once a heart attack, the onset of the disease is acute, angina, or myocardial infarction. Some people have lost their precious lives before they can be rescued. People who stay up late may experience temporary ischaemia and hypoxia of the myocardium and angina pectoris. At night, the blood is in a state of high coagulation, and it is also easier to form blood clots, which can lead to strokes and heart attacks and so on. In addition, staying up late can affect cardiovascular health and increase the risk of sudden cardiac death in the general population.

　　▶ Increase the probability of infertility

　　Various hormones required by the human body are secreted most vigorously at night, and women often stay up late will lead to changes in the hormonal environment of the body. Once the estrogen secretion is insufficient for a long period of time, it will cause persistent amenorrhoea, uterine atrophy, osteoporosis, etc. due to the decline of ovarian function. Even if the treatment and conditioning to return to normal, it will also have a certain impact on the next generation. Men stay up late for a long time, so that the body's hormone level disorders, endocrine disorders, may cause infertility.

　　What is the best time to sleep?

　　"Early to bed, early to rise, good health" is not just a slogan, change the bad habits of staying up late has been urgent. A person's deep sleep is usually between 12pm and 3am. However, the body usually takes more than one hour of sleep to reach a deep sleep state, so the best time for people to sleep is from 9pm to 11pm.

　　In addition, from 12pm to 2am, the liver is highly active to eliminate metabolic wastes and toxins, and this period is also known as the "detoxification period" or "beauty time". Therefore, it is best to go to sleep before 11 o'clock to achieve health and beauty effects. If you have time to sleep for half an hour at noon, it is also very beneficial to the body.