Science-based sleep timing
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every single morning
Find your perfect bedtime or wake-up time based on your natural 90-minute sleep cycles. Never feel groggy again.
Your ideal times
Your sleep night — visual breakdown
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Every sleep problem, solved
Specialized calculators for every kind of sleeper. All free. All science-backed.
Sleep Calculator
Find your ideal bedtime or wake-up time based on 90-minute cycles, age, and how quickly you fall asleep.
sleep cycle calculator • bedtime calculatorFlip the Clock
Night shift sleep sync — custom schedules for 1st, 2nd, and 3rd shift workers who refuse to feel wrecked.
night shift sleep schedule • swing shift bedtimeJet Lag Calculator
Enter your route. Get a day-by-day plan 3 days before, during, and after your flight — light, meals, melatonin timing.
jet lag recovery calculator • flight sleep planCouples Sleep Sync
Different bedtimes, snoring, different chronotypes — get a compromise schedule that lets both of you actually sleep.
sleep schedule for couples • snoring partnerSleep Debt Recovery
Had a rough week? Calculate your sleep debt and get a 7-night rebuild plan that restores you without wrecking tomorrow.
recover from sleep debt • catch up on sleepShift Rotation Planner
Enter your 28-day rotation pattern. Get a custom sleep plan for every shift transition, including anchor sleep strategies.
nurse rotating shift sleep schedule • 12-hour shift planEvery wake-up time covered
Find your exact schedule
Dedicated sleep guides for every wake-up time — packed with science, schedules, and tips.
The science
How sleep cycles work
Why the timing matters as much as the total hours.
You cycle through stages
Every night your brain moves through N1 light sleep, N2 true sleep, N3 deep restorative sleep, and REM dream sleep — then the whole thing repeats 4–6 times.
Each cycle is ~90 minutes
One complete cycle takes between 80–120 minutes. Most adults complete 4–6 cycles in a healthy night, with deep sleep front-loaded and REM back-loaded.
Waking mid-cycle = groggy
If your alarm fires during deep N3 sleep, you feel disoriented for 30–60 minutes. This is called sleep inertia — and it's entirely avoidable with timing.
Wake at the right moment
By timing your alarm to land at the natural end of a cycle — during light N1 sleep — you wake clear, refreshed, and ready. That's the whole trick.
Night shift sleep sync
Flip the Clock
Working against the sun doesn't mean you have to feel wrecked. Pick your shift, get a custom sleep plan.
1st Shift — Day Worker
Typical schedule: 6:00 AM – 2:00 PM
- 1Target bedtime: 9:30–10:00 PM. That gives you 5 full cycles before a 6 AM alarm. Count back 7.5 hours + 15 min fall-asleep time.
- 2Morning light within 15 minutes of waking. Open blinds immediately or step outside. This anchors your circadian rhythm and prevents the "zombie until coffee" feeling.
- 3Caffeine cutoff at noon. Your 2 PM soda or post-lunch coffee still has half its caffeine in your system at 7 PM. Cut it early for faster sleep onset.
- 4Weekends: don't oversleep by more than 90 minutes. Sleeping in 3–4 hours on Saturday destroys your Monday. Keep wake times within one cycle of weekdays.
2nd Shift — Swing Worker
Typical schedule: 2:00 PM – 10:00 PM
- 1Two options: sleep early OR sleep late — don't split the difference. Either 1:00 AM → 8:30 AM (7.5 hrs before work prep) or 2:00 AM → 9:30 AM. Commit to one.
- 2Use blackout curtains — non-negotiable. Sleeping past sunrise means fighting your biology. Blackouts + cool room (67°F) = actual deep sleep.
- 3Strategic nap before shift: 20 or 90 minutes, not in between. A 20-min power nap at 12:30 PM boosts alertness without sleep inertia. A full 90-min cycle works too.
- 4Delay bright light on your drive home. Sunglasses at 10 PM. Bright light suppresses melatonin — you need to preserve it so you can fall asleep when you get home.
- 5On days off: pick ONE anchor wake time and stick to it. Shifting 3 hours every day off causes permanent social jet lag.
3rd Shift — Night Worker
Typical schedule: 10:00 PM – 6:00 AM
- 1Anchor sleep: 8:30 AM → 4:00 PM (5 cycles). Sleeping during daylight means fighting biology — you need the full toolkit to make this work.
- 2Bright light blast when you wake up at 7:30 PM. Use a 10,000 lux lamp for 30 minutes. This tricks your brain into thinking it's morning and sharpens alertness for your shift.
- 3Blue-blocking glasses after 4 AM. Your shift ends at sunrise — protect your melatonin so you can sleep when you get home. Amber glasses are cheap and effective.
- 4Bedroom setup: blackout curtains + white noise + cool room (65–67°F). All three are non-negotiable for day sleeping. Any missing piece tanks your deep sleep.
- 5Caffeine: last cup by 2 AM, no later. Caffeine 4 hours before your target bedtime destroys sleep quality even if you fall asleep quickly.
- 6Anchor nap before shift: 90 minutes at 7:00 PM. This "prophylactic nap" reduces fatigue during the 3–6 AM danger window when most night-shift accidents happen.
- 7On days off: DON'T flip back to day schedule. The flip-flop between day/night sleep on days off is the #1 cause of chronic fatigue in 3rd shift workers. Keep anchor sleep consistent.
Deep dive
The science of sleep
A quick primer on what's happening in your brain every night.
Your brain on sleep: what actually happens
Here's the thing almost nobody realizes: when you fall asleep, your brain doesn't power down — it gets busier. What looks like hours of doing nothing is actually a tightly choreographed 90-minute performance in four acts, repeating four to six times a night. Understanding that choreography is the difference between waking up sharp and waking up like a reanimated corpse.
Every cycle moves through four distinct stages, and each one is doing a completely different job:
N1 — Light Sleep: The doorway between awake and asleep. Home of the hypnic jerk, that "falling off a cliff" twitch. Waking here is gentle.
N2 — True Sleep: The workhorse — roughly half your night. Sleep spindles fire and the day's memories get quietly filed away.
N3 — Deep Sleep: Your body's repair shift. Growth hormone, tissue recovery, and the brain's literal nightly waste-flush all happen here — and it's heavily front-loaded into the first few cycles.
REM — Dream Sleep: The overnight therapist. Emotional processing, creativity, and vivid dreams — and it's back-loaded, which is exactly why cutting sleep short robs you of REM specifically.
The full deep dive covers why deep sleep clears Alzheimer's-linked proteins, what sleep inertia really is, and the simple rule that makes 7.5 hours often beat 8.
Common questions