Find the best bedtime or wake-up time based on natural 90-minute sleep cycles. Wake up feeling refreshed by aligning your alarm with the end of a complete sleep cycle instead of mid-cycle.
One sleep cycle lasts about 90 minutes and includes light sleep, deep sleep, and REM stages. Most adults need 5-6 complete cycles (7.5-9 hours) per night.
You may be waking up in the middle of a deep sleep phase. Aligning your alarm to the end of a 90-minute cycle helps you wake during light sleep, feeling more alert.