Sleep
Health
Calculate optimal wake-up & bedtimes to wake up feeling refreshed and energized every day.
When do you need to wake up?
Sleep
Science
Restore Circadian Rhythm
Circadian Health
Sleep Optimization Tools
The Process
of Deep
REM Sleep
Optimizing
Your Sleep
Cycles
Sleep Science
Groundedinhumancircadianbiologyand90-minuteultradianrhythmcycles,ourprecisioncalculatoralignsbedtimeandwaketimingtoeliminatemorninggrogginessandmaximizedailyenergy.Calculateyouridealsleepwindownow!
Services
Sleep Cycle Calculation
Computes backward or forward from your wake-up alarm in precise 90-minute ultradian blocks, factoring in an average 14-minute sleep onset latency so you wake during Stage 1 light sleep without grogginess.
REM & Deep Sleep Synchronization
Analyzes non-REM Stage 3 slow-wave sleep and REM phases to optimize brain wave repair, memory consolidation, physical tissue recovery, and emotional regulation.
Circadian Rhythm Reset Protocol
Provides science-backed timing recommendations for morning sunlight exposure, evening blue-light cutoffs, and body temperature regulation to synchronize your master clock.
Chronotype Profile & Latency Mapping
Customizes sleep timing windows based on whether you are a Lion, Bear, Wolf, or Dolphin chronotype, adjusting for individual latency and Adenosine sleep pressure.
Sleep Debt & Recovery Planning
Calculates accumulated sleep deficits from consecutive late nights and constructs a safe, non-disruptive catch-up schedule that prevents circadian rhythm fragmentation.
Project
Circadian Bedtime & Wake Matrix
Algorithmic sleep schedule matrix designed to match 5–6 full 90-minute sleep cycles with custom morning alarms, avoiding sleep inertia.
REM Stage & Latency Optimizer
Baseline calculation model adjusting for individual time-to-fall-asleep metrics and deep slow-wave sleep boundaries.
Chronotype & Melatonin Window Suite
Evening wind-down timing protocols, caffeine cutoffs, and dim-light melatonin onset (DLMO) calculator for optimal sleep hygiene.
Latest Research
Dive deeper into the biological mechanisms of rest. Read our science-backed guides on circadian rhythms, sleep debt, and falling asleep faster.
Explore All Sleep Tools
Frequently Asked Questions
What time should I go to bed if I wake up at 6 AM?+
If you need to wake up at 6 AM, the best bedtimes to complete full 90-minute sleep cycles are 8:46 PM (for 9 hours of sleep), 10:16 PM (for 7.5 hours of sleep), or 11:46 PM (for 6 hours of sleep). These times include 14 minutes to fall asleep.
How long is a full sleep cycle?+
A full sleep cycle lasts approximately 90 minutes. During this time, your body moves through light sleep, deep sleep, and REM sleep. Waking up at the end of a cycle helps you feel refreshed rather than groggy.
Can I catch up on missed sleep?+
Yes, you can recover from short-term sleep debt by sleeping a little longer the next few nights or taking a 90-minute nap. However, chronic long-term sleep debt cannot be completely erased just by sleeping in on the weekends.
Is it better to wake up early or sleep in?+
It is better to maintain a consistent wake-up time every day, even on weekends. Consistency helps regulate your circadian rhythm, making it easier to fall asleep at night and wake up naturally in the morning.
How many sleep cycles should I get per night?+
Most adults do best with 5 complete sleep cycles per night, which works out to 7.5 hours of sleep (not counting the time to fall asleep). Four cycles (6 hours) is often enough for some people but leaves others running a sleep deficit. Six cycles (9 hours) is ideal if you are recovering from illness, intense exercise, or accumulated sleep debt.
What happens if I wake up in the middle of a sleep cycle?+
Waking up mid-cycle — particularly during Stage 3 deep sleep — causes sleep inertia, which is that heavy, foggy feeling that can last anywhere from a few minutes to over an hour. This is why some people feel terrible after 8 hours of sleep if their alarm fires at the wrong moment. Timing your alarm to the end of a cycle avoids this.
Can I use a sleep calculator for naps?+
Yes. Naps follow the same cycle logic. A 20-minute nap keeps you in Stage 1 and 2 (light sleep), which is easier to wake from and does not cause grogginess. A 90-minute nap completes one full cycle, including deep sleep and REM, and is genuinely restorative. Naps between 30 and 60 minutes tend to cause the most grogginess because you wake up mid-cycle.
Does everyone have a 90-minute sleep cycle?+
The 90-minute figure is an average. Individual cycle lengths range from about 80 to 100 minutes. Early cycles are often slightly shorter, later ones slightly longer. For most people, 90 minutes is close enough that using it as a baseline gives useful results.
Is 6 hours of sleep enough for adults?+
For most adults, 6 hours is consistently less than the body needs. Research shows that people sleeping 6 hours a night for two weeks accumulate the same cognitive impairment as going completely without sleep for 24 hours. A small percentage of the population (roughly 1–3%) genuinely thrives on 6 hours due to a genetic variant, but it is rare.
What is sleep debt and can you pay it back?+
Sleep debt is the accumulated difference between how much sleep you needed and how much you got. You can recover from short-term sleep debt by sleeping longer over the following days. Chronic, long-term sleep debt is harder to fully reverse. The best approach is to prevent debt from accumulating rather than trying to pay it back in bulk.