The issue with sleep quality has to do with the brain's sleep rhythm. The science shows you cannot change the brain's sleep rhythm whether you are a natural early bird or a night owl. It has nothing to do with how you feel. It is about how the brain behaves during sleep. They see a range of rhythm for early risers (4 to 6 am) to late risers (8 to 9 am). The wake up time governs the go to sleep time. The later risers should be sleeping by 12 midnight for proper brain sleep. It is based on how the brain recognizes the light of day.