TempoLife › Sleep calculator › Wake at 18:00
What time to go to bed to wake up at 18:00
To wake at 18:00 feeling rested, be in bed by 08:45 (six 90-minute sleep cycles — 9 hours) or 10:15 (five cycles — 7.5 hours). Both include the ~15 minutes an average adult takes to fall asleep.
All bedtimes for a 18:00 alarm
| Go to bed at | Sleep cycles | Actual sleep | Verdict |
|---|---|---|---|
| 08:45 | 6 | 9 h 00 min | Fully rested |
| 10:15 | 5 | 7 h 30 min | Good for most adults |
| 11:45 | 4 | 6 h 00 min | Short — fine occasionally |
| 13:15 | 3 | 4 h 30 min | Emergency only |
Assumes 90-minute average cycles and 15 minutes to fall asleep. Your cycles may run 80–100 minutes — if you consistently wake groggy, shift bedtime by 15 minutes and re-test.
How to actually make the 08:45 bedtime happen
The bedtime is arithmetic; keeping it is behaviour. Three things move the needle most: a fixed wake time (including weekends, within an hour), no sizeable caffeine within 8 hours of lights-out — check your own cutoff with the caffeine calculator — and dimming screens in the last half hour. If you are chronically under five cycles, the sleep debt calculator shows what the week is really costing you.
Track your real sleep, not the plan
TempoLife syncs sleep from Google Health Connect and shows your actual nights against your target — alongside food, steps and weight. Free to start.
Frequently asked questions
What time should I go to bed to wake up at 18:00?
Aim to be in bed by 08:45 for six full sleep cycles (9 hours of sleep) or 10:15 for five cycles (7.5 hours), assuming a typical 15 minutes to fall asleep. Waking at the end of a 90-minute cycle feels noticeably easier than waking mid-cycle.
How many hours before 18:00 should I stop caffeine?
Working back from a 10:15 bedtime, keep the last sizeable coffee at least 8 hours earlier — caffeine's ~5-hour half-life means a 15:00 mug still leaves a third of its caffeine at a 10:15 lights-out.
Why count sleep in 90-minute cycles?
A full night cycles through light, deep and REM sleep roughly every 90 minutes. Waking at a cycle boundary — from light sleep — feels easier than being pulled out of deep sleep mid-cycle. The 90 minutes is an average; your own cycles may run 80–100 minutes, so treat the grid as a starting point.
