If a normal person sleeps only 6 hours a day, but the deep sleep phase is sufficient is possible and in a normal situation. Normal adult sleep time is 6-8 hours a day is appropriate, but if only 6 hours a day, the deep sleep phase must be more than 4 hours, light sleep phase should be less than 3 hours, the long sleep time in 6 hours a day, also will not cause adverse effects on the body, and will not cause irreversible damage to the nervous system. If you only sleep 6 hours a day, and the deep sleep time is significantly less than 4 hours, and the light sleep time is more than 3 hours, it will cause fatigue, weakness, poor concentration, memory loss or emotional anxiety, irritability, irritability and other obvious lack of sleep and rest, and there will also be, for example, low immune function, physical fatigue, and easy infection.