Based on 90-Minute Sleep Cycles · Free · No Sign-Up

Bedtime Calculator —
What Time Should I Go to Sleep?

Enter your wake-up time below. We calculate the best bedtimes based on 90-minute sleep cycles so you wake at the end of a cycle feeling naturally alert — not groggy. Results highlight the optimal 5-cycle bedtime recommended for most adults.

We account for the average 14 minutes to fall asleep

10:46 PM
optimal bedtime for 6:30 AM wake
7.5 hrs
recommended sleep (5 cycles)
14 min
avg. time to fall asleep

Quick Reference

Bedtime for Common Wake-Up Times

Find your wake-up time in the table below. The highlighted column (5 cycles) is the recommended bedtime for most adults.

Wake-Up Time 3 Cycles (4.5 hrs) ⚠️ 4 Cycles (6 hrs) ✅ 5 Cycles (7.5 hrs) ⭐ 6 Cycles (9 hrs)
5:00 AM 12:16 AM 10:46 PM 9:16 PM 7:46 PM
5:30 AM 12:46 AM 11:16 PM 9:46 PM 8:16 PM
6:00 AM 1:16 AM 11:46 PM 10:16 PM 8:46 PM
6:30 AM 1:46 AM 12:16 AM 10:46 PM 9:16 PM
7:00 AM 2:16 AM 12:46 AM 11:16 PM 9:46 PM
7:30 AM 2:46 AM 1:16 AM 11:46 PM 10:16 PM
8:00 AM 3:16 AM 1:46 AM 12:16 AM 10:46 PM
8:30 AM 3:46 AM 2:16 AM 12:46 AM 11:16 PM
9:00 AM 4:16 AM 2:46 AM 1:16 AM 11:46 PM

All times account for 14 minutes average sleep onset. ⭐ = Optimal for most adults.

What time should I go to bed?

The best bedtime is exactly 7 hours and 44 minutes before your alarm — that is 7.5 hours of sleep plus 14 minutes to fall asleep. This covers 5 complete 90-minute sleep cycles, which is the CDC-recommended amount for adults aged 18–64.

Common examples: if you wake at 6:00 AM, go to bed at 10:16 PM. If you wake at 6:30 AM, go to bed at 10:46 PM. If you wake at 7:00 AM, go to bed at 11:16 PM. If you wake at 7:30 AM, go to bed at 11:46 PM.

If 7.5 hours is impossible on a given night, 6 hours (4 cycles, bedtime 6h 14min before wake-up) is the next best option. Avoid consistently sleeping fewer than 6 hours — the cognitive and health costs compound quickly.

Sleep Science

Why Bedtime Matters More Than You Think

Most people focus on how long they sleep, but when you sleep is equally important. Your bedtime influences three interconnected systems: your circadian rhythm, your sleep architecture, and your hormonal environment.

Circadian rhythm is your body's internal 24-hour clock, driven by light, temperature, and social cues. Melatonin — the hormone that signals sleep readiness — typically rises around 9–10 PM in adults who keep regular schedules. Sleeping too far outside this window means fighting your circadian biology, resulting in lighter, less restorative sleep even if your total hours are adequate.

Sleep architecture describes the distribution of sleep stages across the night. Deep N3 sleep dominates the first half of the night, while REM sleep dominates the second half. Going to bed late means you miss peak deep sleep time; waking too early means cutting off REM. Both have measurable consequences for physical recovery and cognitive function.

Growth hormone is released almost exclusively during the first deep sleep cycle, typically within 90 minutes of falling asleep. This makes the start of your sleep especially important for tissue repair, immune function, and metabolic health — regardless of total sleep time.

Tips for Sticking to Your Bedtime

⏰
Set a bedtime alarm
Set a phone reminder 30–45 minutes before your target bedtime. Treat it as seriously as your morning alarm. Many people who struggle with sleep have no issue with wake time but forget to protect their bedtime.
🌡️
Start your wind-down routine early
Begin dimming lights and reducing screen use 60 minutes before bed. Bright light — including phone and TV screens — delays melatonin release and makes it harder to fall asleep at your target time.
📅
Anchor weekends to weekdays
Sleeping in on weekends shifts your circadian clock backward (social jet lag) and makes Monday mornings harder. Allow yourself a maximum of 60 minutes deviation from your weekday schedule on weekends.
🍵
Time your last coffee carefully
Caffeine has a half-life of 5–6 hours. To fall asleep by 10:30 PM, have your last caffeinated drink before 2:30 PM. Even coffee taken at 3–4 PM can delay sleep onset by 30–60 minutes for sensitive individuals.
📵
Leave your phone outside the bedroom
Phones disrupt sleep in three ways: light exposure delays melatonin, notifications fragment sleep, and habitual checking creates psychological arousal incompatible with the calm needed to fall asleep. Charge outside the bedroom.
🛁
Use a warm bath strategically
A warm bath or shower 60–90 minutes before bed raises skin temperature, which — as the body cools — accelerates sleep onset. Research shows this shortens the time to fall asleep by up to 36%.

How Bedtime Affects Your Night

The Ideal Sleep Window: 10 PM to Midnight

9–10 PM
Pre-Sleep Phase
Melatonin rises. Body temperature starts to drop. The ideal time to begin your wind-down routine.
10–11 PM
Optimal Bedtime Window
Cortisol is low, melatonin peaks. Falling asleep here means your first N3 deep sleep cycle aligns with peak growth hormone release.
11 PM–12 AM
Late but Acceptable
Still within the circadian sleep window for most adults. You may notice slightly reduced deep sleep in cycle 1 compared to an earlier bedtime.
After Midnight
Suboptimal Territory
Rising cortisol in the early morning hours competes with melatonin. Sleep is lighter and less restorative. REM is compressed if you wake before 8 AM.

Note: "Night owls" (delayed chronotype) have a naturally later melatonin onset and may optimally sleep 12 AM–8 AM or later. Chronotype is partly genetic. If you genuinely cannot fall asleep before 1–2 AM despite good sleep hygiene, you may have Delayed Sleep Phase Syndrome — consult a sleep specialist.

Common Questions

Bedtime Calculator FAQ

The best bedtime is 7 hours and 44 minutes before your wake-up alarm — that is 7.5 hours of sleep plus 14 minutes to fall asleep. This covers 5 complete 90-minute sleep cycles, which is the optimal amount for most adults. For a 6:30 AM wake-up, go to bed at 10:46 PM. For 7:00 AM, go to bed at 11:16 PM. Use the calculator above to find the exact time for your schedule.
You need at least 7.5 hours in bed (plus 14 minutes to fall asleep = 7 hours 44 minutes total) to feel reliably rested. Going to bed at exactly the right time matters as much as total duration — the calculator above ensures your bedtime aligns with the end of a complete 90-minute sleep cycle, so your wake time coincides with light sleep.
Both matter, but in different ways. Total sleep duration determines how many cycles you complete (critical for physical and mental restoration), while bedtime timing affects your circadian alignment. Research consistently shows that sleeping in phase with your biological clock — going to bed when melatonin is high — produces deeper, more restorative sleep than the same number of hours taken out of phase.
A chronically late bedtime disrupts circadian alignment, reduces slow-wave (deep) sleep in the first half of the night, and compresses REM in the second half when morning commitments force early waking. This explains why night owls often feel less rested than early sleepers even with equivalent total hours. Consistently late bedtimes are also associated with higher rates of depression, anxiety, obesity, and type 2 diabetes.
For most people, an earlier bedtime is preferable to a later wake time, because early sleep captures peak slow-wave sleep and growth hormone release. However, if your chronotype is genuinely late (you cannot fall asleep before midnight despite good sleep hygiene), then sleeping from midnight to 8 AM is better than forcing an early bedtime and lying awake. Respect your chronotype but avoid making it worse by staying up late when you do not need to.
Feeling tired despite correct bedtime timing suggests sleep quality issues: sleep apnoea interrupting cycles, stress or anxiety elevating cortisol through the night, poor sleep environment (too warm, too noisy, too light), alcohol disrupting REM sleep, or accumulated sleep debt that requires several nights of good sleep to repay. If daytime fatigue persists despite 7–9 hours of sleep, consult a doctor to rule out sleep disorders.

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Find Your Perfect Bedtime Now

Enter your wake-up time above and we calculate the exact bedtime you need for 5 complete sleep cycles.