In recent years, more and more people are drinking milk at night, because milk contains tryptophan, which can help with sleep. This practice is undoubtedly suitable for most people, but for those with kidney stones or a history of them, it's a different story.
The vast majority of kidney stones are composed of calcium oxalate. Excessive intake of animal protein and dairy products can significantly increase the levels of calcium and oxalate in the urine.
This facilitates the formation and recurrence of kidney stones. At night, it is the peak period for the excretion of stone-forming components. If you drink milk at this time, the milk is high in calcium. And 2-3 hours after drinking milk is the peak time for calcium to be excreted through the kidneys. If you are asleep at this time, the urine becomes concentrated, and the increased amount of calcium passing through the kidneys can easily lead to stone formation.
Therefore, it is best not to drink milk at this time. It is advisable to drink 500 ml of water before bedtime and then another 200 ml after waking up to urinate. In daily life, drinking water frequently throughout the day to ensure a urine output of about 2500-3000 ml is also beneficial for preventing kidney stones.