It is said that milk contains a compound called L- tryptophan, which can make people feel tired and sleepy. L- tryptophan is the main raw material for brain to synthesize serotonin, which can temporarily inhibit brain thinking activities, thus making people want to sleep. So drinking milk at night is good for people's rest and sleep. Really? Tryptophan is an important nutrient and one of the essential amino acids. As a protein-rich beverage, milk does contain L- tryptophan, which can also be used to make sleep-inducing hormones serotonin and melatonin. This may also be the reason why this rumor is widely known-it does have certain scientific basis. In addition to milk, meat also contains tryptophan widely, and the total amount of tryptophan contained in a small number of foods is generally not enough to make the body's hormone level fluctuate. In order to protect our fragile brain, the capillary structure of the brain prevents many blood compounds from entering the brain tissue, which is the so-called blood-brain barrier. Any substance that wants to produce a sleep effect must first be able to cross the blood-brain barrier before reaching the brain. But milk is rich not only in tryptophan, but also in other amino acids. In 2003, MIT researchers published a paper in the American Journal of Clinical Nutrition, saying that eating milk, a food rich in protein, would actually reduce the ability of tryptophan to cross the blood-brain barrier. Eat some biscuits instead of milk. Carbohydrate can stimulate the synthesis of insulin, and insulin can help other amino acids except tryptophan enter the muscle tissue from the blood, so that tryptophan does not compete with other amino acids for the passage across the blood-brain barrier, so tryptophan entering the brain increases and people become sleepy. In addition, another reason why people often feel sleepy after a full meal is that eating makes blood flow to the digestive tract, which reduces blood supply to the brain and causes fatigue and drowsiness. But liquid food is obviously not as effective as solid food. If you use a big bowl of midnight snack instead of milk, it may be easier to fall asleep (but it is also easier to understand what "the horse has no night grass and is not fat") ... Taking tryptophan on an empty stomach can also ensure that enough hypnotic tryptophan enters the brain. In the United States, there is a separate L- tryptophan food supplement (about 65,438+0,000-2,000 mg per day) for the treatment of insomnia, depression and other problems. However, in 1989, FDA urgently recalled this supplement in circulation because it was found that this supplement may cause eosinophilic myalgia syndrome, including high fever, rash, weakness and shortness of breath. In those years, the disease affected 1500 people and claimed 37 lives. The relationship between this disease and L- tryptophan complementary food is still inconclusive, and some people suspect that it is caused by pollution in the production process. As for whether the calories of milk contribute to sleep. Indeed, studies have shown that the sleep rate increases with the increase of skin temperature. But many times, a glass of milk in the gastrointestinal tract is not enough to warm your skin. A hot bath will be much more effective. In a word, the hypnotic effect of milk is mainly psychological placebo effect. If you continue to believe this, then milk may really be effective for your insomnia.