How do I calculate my ideal bedtime?

Begin with the time you need to wake up and count backward by seven to nine hours, depending on your usual sleep requirement. Add another 15 to 30 minutes to allow yourself time to fall asleep. For example, if you need to wake at 7:00 a.m. and want eight hours of actual sleep, aim to be asleep by 11:00 p.m. You may need to get into bed around 10:30 or 10:45 p.m. A sleep-cycle calculator might suggest times based on estimated 90-minute cycles, but these are only rough guides. Test your schedule for one or two weeks. If you remain tired or struggle to wake, move bedtime earlier in 15-minute steps.