Why is waking up at the end of a sleep cycle better than in the middle?
Because sleep passes through phases of different depth within each cycle. Waking up during deep sleep causes grogginess and confusion known as "sleep inertia," while waking up at the end of a full cycle noticeably reduces this feeling.
Is the cycle exactly 90 minutes for everyone?
No, this is just a common average. The actual duration ranges roughly between 70 and 120 minutes and varies from person to person. Use the result as a rough starting point, not a precise guaranteed number.
How many sleep cycles are recommended?
Sleep experts generally recommend 5-6 cycles for most adults (7.5-9 hours). The calculator highlights the 5-cycle option as a recommended starting point, while also showing 3, 4, and 6-cycle options.
Does the calculated time include the time to fall asleep?
Yes, an estimated duration (15 minutes by default, adjustable) is automatically added to account for the time actually needed to fall asleep after getting into bed.
