The best time for children to take calcium tablets is at night before going to bed, because during the daytime 1 day 3 meals, the body can take in 300-400mg or even more calcium from food, when the body excretes calcium from the urine through the calcium regulation mechanism, the blood can always be replenished from food to maintain the blood calcium level. At night, the body no longer eats, and urine is formed as usual, so part of the calcium in the blood continues to enter the urine, so in order to maintain normal blood calcium levels, the body has to use the calcium in the bones, the result of this internal self-mediation is that most of the calcium in the urine every morning comes from bone calcium. The various hormones that regulate blood calcium levels in the body are secreted differently during the day and at night, so blood calcium levels are generally lower at night. Therefore, in this case, it is recommended to take calcium before going to bed to provide a source of calcium for calcium regulation at night, blocking the body from using bone calcium, and calcium contains a sedative effect, which helps sleep.