Find the best bedtime for your wake time.
Working backwards from a fixed wake time is more reliable than working forwards from bedtime. Sleep arrives in cycles of roughly ninety minutes, so aiming to wake at a cycle boundary avoids being pulled out of deep sleep. The time it takes you to fall asleep is added on top, because time in bed is always longer than time asleep.
Bedtime from wake time
Bedtime = wake time - (cycles x cycle length) - minutes to fall asleep
These figures are estimates based on population-average formulas and are intended for training and recreational planning only. They are not medical advice. Consult a qualified health professional before starting or changing an exercise programme, particularly if you have an existing medical condition.
Count back from your wake time in ninety-minute blocks and add your usual time to fall asleep. Five cycles plus fifteen minutes of onset is about seven and three-quarter hours in bed.
No — they range from about 70 to 110 minutes and lengthen through the night. Treat cycle timing as a useful approximation rather than a precise schedule.
Total sleep matters most. Cycle alignment mainly affects how groggy you feel on waking, which is why the one-cycle-shorter option is shown too.