For the time of beauty sleep, it means that you should go to bed immediately after 21:00 p.m. The time of beauty sleep means that you must enter the deep sleep phase at 1-3:00 a.m. If you want to enter the deep sleep phase, you need to go through 3-4 hours of light sleep phase transition, so go to bed at 21:00 pm, after 3 hours from light sleep to deep sleep phase transition, so at 1-3:00 am to ensure that you enter the deep sleep phase, for the body and skin whitening, as well as exfoliation and the skin have a very good effect, but also to increase the elasticity of the skin, slow down the aging of the skin It can also increase skin elasticity, slow down skin aging, reduce melanin production, so this time is called the time to sleep beauty sleep.