Your body runs on an internal clock, or circadian rhythm, which affects the quality of your sleep based on when you fall asleep — not just how long you sleep. Going to bed at odd hours or shifting your sleep schedule frequently can confuse your body and reduce sleep quality.
Sleep works best when it happens in full cycles — roughly 90-minute blocks. That's why our Sleep Time Planner recommends specific bedtimes based on your chosen wake-up time: to help you wake up at the end of a cycle, not in the middle of one.