Choose the time you usually go to bed. Each page gives the wake-up times that finish a complete sleep cycle, how many hours of sleep each one really is, and what to do when the night is shorter than it should be. 15 minutes to fall asleep is already built in. Know your alarm time instead? Start from bedtimes by wake-up time, or use the sleep calculator for any other time.
How the wake-up times are worked out
Each time is your bedtime, plus 15 minutes to fall asleep, plus a whole number of 90-minute cycles. Four cycles is six hours, five is seven and a half, six is nine. Most adults need five or six. The 90-minute figure is an average — your own cycles may be a little shorter or longer — so treat the times as a starting point and adjust by 15 minutes if you still wake up groggy.
Wake up at the end of a cycle
MathWake tracks your sleep with your phone’s motion and sound, shows your cycles each morning, and wakes you with an alarm that rings on silent mode and will not stop until you finish a wake-up mission.
Download MathWake for iPhone