If you have ever set an alarm and then wondered what time to go to bed, a bedtime chart is a quick way to work backwards. The chart below uses the same assumptions as the calculator on this site: a sleep cycle of about 90 minutes and 15 minutes to fall asleep. It is a planning aid, not a measurement of your individual sleep.
How the bedtime chart is calculated
The calculator subtracts one sleep cycle at a time from your wake-up time. Each 90-minute cycle is followed by a 15-minute allowance for falling asleep, so the formula is:
bedtime = wake-up time − (cycles × 90 minutes + 15 minutes)
Four cycles is about six hours of sleep, five is about seven and a half hours, and six is about nine hours. Most adults are advised to get seven to nine hours, so the five- and six-cycle columns are the usual starting points. The four-cycle column is included for short nights, not as a target.
Bedtime chart for common wake-up times
The table uses a 24-hour clock. Times from 19:45 to 23:45 are the previous evening; times from 00:15 to 02:45 are after midnight.
| Wake-up time | 4 cycles (≈6 h) | 5 cycles (≈7.5 h) | 6 cycles (≈9 h) |
|---|---|---|---|
| 05:00 | 22:45 | 21:15 | 19:45 |
| 05:30 | 23:15 | 21:45 | 20:15 |
| 06:00 | 23:45 | 22:15 | 20:45 |
| 06:30 | 00:15 | 22:45 | 21:15 |
| 07:00 | 00:45 | 23:15 | 21:45 |
| 07:30 | 01:15 | 23:45 | 22:15 |
| 08:00 | 01:45 | 00:15 | 22:45 |
| 08:30 | 02:15 | 00:45 | 23:15 |
| 09:00 | 02:45 | 01:15 | 23:45 |
Read the row for your wake-up time. If you want about seven and a half hours of sleep, start with the five-cycle column. If you regularly need closer to nine hours, use the six-cycle column.
How to read the chart
The 15-minute allowance is an average, not a rule. If you usually fall asleep within five minutes, you can go to bed a little later. If you often lie awake for half an hour, the bedtime in the chart may be too late for the sleep you are trying to get.
Treat the chart as a starting range. The useful test is how you feel over one to two weeks: steady daytime energy, no strong urge to sleep during the day, and a wake-up time you can keep on most days. Adjust the bedtime by 15 to 30 minutes at a time rather than chasing a perfect number.
If your wake-up time is not in the table
Use the same formula or the sleep cycle calculator. For example, if you wake at 06:40 and want five cycles: five cycles plus the 15-minute allowance is 465 minutes, or 7 hours 45 minutes. 06:40 minus 7:45 is 22:55 the previous evening.
The arithmetic is simple, but doing it while you are tired is not. The calculator on the home page applies the same calculation to any wake-up or bedtime you choose.
What the chart cannot tell you
- It cannot measure your actual cycle length. Cycles commonly range from about 70 to 120 minutes; 90 minutes is an average used for planning.
- It cannot detect insomnia, sleep apnea, restless legs, or other sleep disorders.
- It cannot guarantee that you will wake up refreshed. Sleep duration, consistency, stress, alcohol, caffeine, illness, and many other factors matter.
- It is not medical advice. If you have persistent trouble sleeping or severe daytime sleepiness, talk to a clinician.
Why waking at the end of a cycle may help
Waking in the middle of deep sleep can leave you groggy for a short time; this is called sleep inertia. Some people find that planning a wake time near the end of a cycle reduces that feeling. The evidence for precisely timing an alarm to a 90-minute cycle is limited, and cycles are not perfectly regular. Treat the chart as a heuristic that may help, not a guarantee.
If you want to understand the cycle itself, read how many sleep cycles you need or the evidence-based guide to sleep duration by age.
How to make the schedule stick
- Keep your wake-up time consistent, including weekends, as much as your life allows.
- Get bright light soon after waking and dim the lights before bed.
- Limit caffeine in the afternoon and alcohol close to bedtime.
- Give yourself a short wind-down routine; the goal is to make the 15-minute allowance realistic.
- Keep the bedroom cool, dark, and quiet.
For more practical adjustments, see the evidence-based sleep tips. If you regularly cannot fall asleep or stay asleep, the insomnia guide covers when to seek help.
Sources
These sources support the general information about sleep duration and sleep cycles. The 90-minute cycle and 15-minute onset are the calculator's simplifying assumptions, not a universal rule.