Tell the calculator when you need to wake up, and it works backwards through 90-minute sleep cycles (plus 15 minutes to fall asleep) to show the best times to go to bed. Pick the bedtime that gives you 5–6 full cycles to wake up at the end of a cycle rather than in the middle of one.
Choose your mode, enter a time, and press Calculate to find optimal sleep times.
A doctor can discuss your symptoms and help you decide what to do next.
