Usually deep sleep time should be more than 4 hours to be healthy, but deep sleep time requires a circadian rhythm, it is recommended to enter deep sleep time at 2-3 am every day, so normal adults are recommended to sleep between 6-8 hours a day. But to enter sleep at 22:00 pm, because the transition from light sleep phase to deep sleep time needs to be carried out for about 3-4 hours, through the transition of about 3-4 hours of time, at 2-3 am to be able to deep sleep. So every day to ensure both the time of sleep, but also to ensure the circadian rhythm of deep sleep, for the normal sleep belongs to the best and the most healthy.