What time should I go to bed?
Work backward from your wake-up time in 90-minute cycles. For a 7 AM alarm, that's roughly 11:15 PM (7.5h) or 9:45 PM (9h) — plus 15 minutes to fall asleep.
“What time should I go to bed?” is the wrong question to ask on its own — because the answer depends entirely on when you need to wake up. Bedtime isn’t a fixed hour; it’s a countdown from your alarm.
Here’s the short version: pick your wake-up time, then count backward in 90-minute sleep cycles and add about 15 minutes to fall asleep. Five cycles (7.5 hours of sleep) suits most adults; six cycles (9 hours) is better if you’re catching up or recovering. For a 7 AM alarm, that lands you at roughly 11:15 PM or 9:45 PM.
Let’s turn that into actual clock times.
What time should I go to bed for my wake-up time?
The math is simple: each cycle is about 90 minutes, you want to wake at the end of one, and you need a buffer to actually drift off. Here are common wake times, already worked out:
| Wake-up time | 6 cycles (9h) | 5 cycles (7.5h) | 4 cycles (6h) |
|---|---|---|---|
| 6:00 AM | 8:45 PM | 10:15 PM | 11:45 PM |
| 6:30 AM | 9:15 PM | 10:45 PM | 12:15 AM |
| 7:00 AM | 9:45 PM | 11:15 PM | 12:45 AM |
| 7:30 AM | 10:15 PM | 11:45 PM | 1:15 AM |
| 8:00 AM | 10:45 PM | 12:15 AM | 1:45 AM |
Each bedtime already includes a 15-minute buffer to fall asleep. The four-cycle column is a short-night fallback, not a target — six hours sits below what most adults need. Want a different wake time or a precise readout? The bedtime calculator does this for any time, and each wake-up page — like wake-up-at-6am or wake-up-at-7am — lists the bedtimes for that exact alarm.
How many cycles should I actually aim for?
For most adults, five complete cycles is the sweet spot. Five × 90 minutes is 7.5 hours of sleep, plus 15 minutes to fall asleep means about 7 hours 45 minutes in bed.
That lines up with the official guidance. The CDC recommends adults get 7 or more hours of sleep a night, and the American Academy of Sleep Medicine puts the range at 7–9 hours for adults aged 18–60. Five cycles lands cleanly inside that window; six cycles (9 hours) is the right call when you’re paying down sleep debt or fighting off illness.
One caveat: 90 minutes is an average. Real cycles run anywhere from 70 to 120 minutes and even vary across a single night. If five-cycle timing leaves you groggy after a week, nudge your bedtime 15 minutes earlier or later and see what fits — more on that in the 90-minute cycle explained.
What if I can’t fall asleep at that time?
A calculated bedtime is a target, not a command — and lying in bed willing yourself to sleep tends to backfire.
If you’re not asleep within about 20 minutes, get up, do something calm in dim light, and come back when you’re sleepy. Forcing it just teaches your brain that bed is where you lie awake. Two things make hitting your bedtime easier:
- Honor your chronotype. If you’re a natural night owl trying to sleep at 9:45 PM, your body clock isn’t ready yet. Find your window with what’s your chronotype and set bedtime near it rather than against it.
- Anchor your wake time first. Counterintuitively, a fixed wake-up time — weekends included — is what makes a consistent bedtime possible, because it stabilizes when sleepiness arrives.
So what time should you go to bed?
Start with the hour your alarm rings. Count back five 90-minute cycles. Add 15 minutes. That’s your bedtime tonight — and if you keep your wake-up time steady, it’ll keep working tomorrow.
Stop picking a bedtime and start picking a wake-up time. The bedtime falls out of the math.