In the recent hit online drama Hidden Corners, Zhou Chunhong has impressed many netizens by forcing her son Zhu Chaoyang to drink hot milk every night. In reality, many people also have the habit of drinking milk before going to bed, because we often hear a saying: drinking milk before going to bed helps sleep.

Is this really the case? If so, how does milk help you sleep? If not, where did the idea that milk helps you sleep come from?

L-tryptophan in milk promotes the secretion of hypnotic substances

'Milk contains L-tryptophan, which helps the body secrete serotonin and melatonin. Li Yun, professor of Shantou University Medical School and director of Shantou University Sleep Medicine Center, told Science and Technology Daily reporter that 5-hydroxytrypsin and melatonin can directly or indirectly promote sleep.

Serotonin, also known as serotonin, was first found in blood serum and is an inhibitory neurotransmitter concentrated in the raphe nucleus of the brain stem. After research, 5-hydroxytryptamine must go through the corresponding receptors to play a role, so far people have found 7 subfamilies of 5-hydroxytryptamine, 14 subtypes, 5-hydroxytryptamine through the activation of different receptors and play different physiological roles.

The head and tail of the raphe nucleus were destroyed separately in rats, and reduced sleep was found in both rats. "This suggests that serotonin is good for sleep, but the exact mechanism is not clear." Li Yun said.

Other studies have found that serotonin has a role in maintaining arousal. "Sleep requires sleep stress, the feeling of wanting to sleep. The longer you stay awake, the stronger the feeling of wanting to sleep. On the other hand, if you stay drowsy, it will be difficult to fall asleep. Li Yun said that serotonin helps maintain wakefulness, which increases sleep pressure to some extent.

In addition, 5-hydroxytryptamine is also used to treat psychological diseases, because when the secretion of 5-hydroxytryptamine is insufficient, it is easy to lead to depression, anxiety and other emotions. "Psychologically speaking, depression and anxiety can affect sleep quality." Li Yun said.

Melatonin, on the other hand, plays a direct role in sleep. "When it gets dark or lights dim, the retina receives less light, and melatonin production increases accordingly, promoting sleep." According to biorhythms, after 10 p.m., melatonin production increases, which increases sleepiness." Li Yun said that when you look at mobile phones and computers at night, you will be exposed to more blue light, and the brain will mistakenly think that it is still daytime, and the secretion of melatonin will be reduced, which will adversely affect sleep.

A previous study from Samyu University in Seoul, South Korea, showed that milk milked at night contains more L-tryptophan and melatonin, chemicals that help people reduce anxiety.

Intake is negligible and the effect is minimal

"In theory, the L-tryptophan in milk can produce sleep-promoting substances, and drinking milk can help you sleep." But to put it in perspective, the L-tryptophan you get from a glass of milk is negligible, so you don't get enough serotonin and melatonin to make us sleep better." Li Yun said.

Experts say that if you eat a balanced diet, there is generally no L-tryptophan deficiency, and there is no need to supplement L-tryptophan by drinking milk.

So why does it exist that drinking milk before bed helps you sleep?

This is because drinking milk is easy to produce a sense of fullness, and it is easier to feel sleepy after eating. "This is because after a full meal, the blood returns to the stomach, resulting in insufficient blood supply to the brain and easy to fall asleep." Li Yun stressed that eating too much before going to bed is not good for sleep.

In addition, another reason is that drinking milk before going to bed is usually to drink hot milk, which will make people feel relaxed and comfortable, thus relieving some of the anxiety. It is also believed that drinking milk before going to bed to help sleep may be a psychological effect.

"It is important to note that drinking too much milk before bed, like drinking too much water or eating too much watermelon at night, increases the likelihood of going to the toilet in the middle of the night, which can affect deep sleep." Li Yun said.

In addition, whole milk is high in fat, and drinking it before bed may lead to weight gain. "Drinking about 150 milliliters of skim or semi-skim milk before going to bed will not have a significant impact on weight." Li Yun said it is best to drink milk about one hour before going to bed.

It should not be ignored that some people are not suitable for drinking milk. "Not only should you avoid it before bed, but also during the day." Li Yun said. For example, people who are easy to bloat, many people drink milk will bloat, affecting sleep; Lactose intolerant people who drink milk tend to have diarrhea; People who have had abdominal surgery should not drink milk; Drinking milk will promote the secretion of stomach acid, so people with digestive tract ulcers, cholecystitis and other digestive tract diseases should avoid drinking milk. In addition, patients with milk allergy and urinary system stones should not drink milk.

"All in all, L-tryptophan in milk theoretically contributes to the production of hypnotic substances, but the intake of L-tryptophan from milk is very limited. Also, some people are not comfortable drinking milk."