Since the birth of mankind,we have been used to sunset = darkness = sleeping. The invention of the light bulb was invented for a hundred years, and it has caused a huge change in our sleep habits: the sleep mode has changed from two paragraphs, and the length of sleep has been shortened from ten hours to seven or eight hours.

　　Why? In addition to the nightlife is more abundant, more importantly because of the blue light emitted by lighting and electronic products. There is a photoreceptor cell on our retina, which is mainly responsible for reporting to the brain: “Is it day or night?” And this cell is very sensitive to blue light, so the so-called day and night alternation is simplified into more or less blue in our heads. The problem. When there is a considerable amount of blue light after the night, it will make our body feel that it is "falling time difference", because the health problems caused by the day and night are reversed.

　　Inhibits melatonin secretion, which affects sleep quality

　　Blue light inhibits the production of melatonin. Melatonin is a hormone that is produced from the pineal gland of the brain in the dark, at night. Its function is mainly to lower our blood pressure, glucose, body temperature at night, so that we can have a full and comfortable sleep. Researchers at Harvard University have found that using 2 hours of electronic products with a backlit display before going to bed can cause melatonin to be inhibited by 22%, causing sleep problems such as reduced sleep time and easy interruption. Sleeping at the same time is also more sleepy than people who have less exposure to blue light before going to bed.

　　Affect blood lipids and obesity

　　According to a study published in the American Journal of Epidemiology in 2014, among 100,000 women, 14% of people who are exposed to light at night are overweight, 25% are obese, and 16% have a waist circumference greater than 35 inches (about 88 cm). . It turns out that the blue light signal received by the retina is transmitted to the brain, and the brain thinks that daytime has begun and the body needs to replenish energy. Even if the dinner is normal that night, hunger can still eat extra food and snacks, leading to weight gain. When you face your phone and computer for more than 3 hours at night, your body will start to feel hungry.

　　Make you depressed and children more susceptible

　　A study in the journal Molecular Psychiatry used hamsters for experiments. In the evening, they illuminate them with dim light. After 4 weeks, the hamster lacks energy and is not active. It shows symptoms of depression. For example, the sugar that I usually like to drink now doesn't like to drink. For the human body, blue light can cause abnormal release of hormone cortisol. During the day, the cortisol content in our blood will be higher, to balance our daytime activities and adjust the immune system; at night, under normal circumstances, the content should be reduced, but the light and screen light will cause abnormal release. Cortisol, while his level is too high, will reduce the amount of serotonin that provides a sense of calm and happiness, prone to anxiety symptoms.