Bedtime Calculator
Bedtime calculator: enter your wake-up time and get the exact time you should go to bed — calculated from 90-minute sleep cycles so you wake at the end of a cycle, not the middle. Free, no sign-up required.
Your ideal bedtimes
Based on a 7:00 AM wake-up
Gold border = recommended. Includes 15-min sleep onset.
Common wake times — ideal bedtime (5 cycles / 7.5 hrs)
Why bedtime timing matters: sleep cycles explained
Sleep is not uniform — it occurs in repeating 90-minute cycles, each containing light sleep, deep (slow-wave) sleep, and REM sleep. If your alarm fires mid-cycle — during deep sleep — your brain is flooded with adenosine (sleep pressure) and melatonin, causing sleep inertia: the groggy, disoriented state that can persist for 30–90 minutes. Waking at the end of a cycle means you surface naturally from light sleep and feel alert almost immediately.
The 15-minute sleep onset adjustment accounts for the fact that you are not asleep the moment you get into bed. The average healthy adult takes 10–20 minutes to fall asleep. If you fall asleep much faster (under 5 minutes consistently), it may indicate significant sleep debt. If it regularly takes over 30 minutes, that is worth noting — see our CBT-I guide for difficulty falling asleep.
Five cycles (7.5 hours of actual sleep) is the optimal amount for most Canadian adults. Six cycles (9 hours) suits recovery periods, illness, and heavy training loads. Four cycles (6 hours) is a workable single-night minimum but causes compounding impairment if sustained — research from the University of Pennsylvania found that after 10 days of 6-hour nights, subjects performed as poorly as those kept awake for 24 hours straight.
Bedtime calculator — frequently asked questions
What time should I go to bed?
The best bedtime is 7.5 hours before your wake-up time (5 complete 90-minute sleep cycles) plus however long it takes you to fall asleep. For a 7 AM wake-up with a 15-minute sleep onset: go to bed at 11:15 PM. Use the calculator above for any wake time.
What time should I go to sleep to wake up feeling rested?
Go to bed so that your alarm falls at the end of a 90-minute sleep cycle. Five cycles (7.5 hours of actual sleep + 15 min onset) is optimal for most adults. For a 6:30 AM alarm: 11:00 PM is ideal (5 cycles). The calculator computes this for any wake time.
What time should I go to bed if I wake up at 6 AM?
For a 6:00 AM wake-up: go to bed at 10:15 PM for 5 cycles (7.5 hrs), or 8:45 PM for 6 cycles (9 hrs). These include a 15-minute sleep onset. If you fall asleep faster or slower, adjust accordingly.
What time should I go to bed if I wake up at 7 AM?
For a 7:00 AM wake-up: go to bed at 11:15 PM for 5 cycles (7.5 hrs), or 9:45 PM for 6 cycles (9 hrs). The calculator auto-adjusts for your personal sleep onset time.
Is 6 hours of sleep enough?
Six hours covers 4 sleep cycles — below the recommended minimum for adults. Research shows sustained 6-hour nights produce cognitive impairment equivalent to 24 hours of no sleep after 10 days. Seven to nine hours (5–6 cycles) is the range recommended by the Canadian Sleep Society for adults.
What is the difference between a bedtime calculator and a sleep calculator?
A bedtime calculator starts from your wake time and tells you what time to go to bed. A sleep calculator may also run in reverse — start from your bedtime to tell you when to set your alarm. The GoToSleep.ca sleep calculator does both; this page focuses specifically on answering "what time should I go to bed?" for a given wake time.
Also need to find the best alarm time?
The full sleep calculator runs in both directions — enter a bedtime and find your optimal wake time, or calculate from right now.
Full Sleep Calculator →