Be asleep by
10:00 PM
Longer sleep opportunity
Sleep calculator
Pick the time you need to wake up and see evidence-based sleep-duration targets. BOTH gives you a planning window instead of pretending one exact bedtime can guarantee ideal sleep cycles.
Calculate sleep-duration targets
Start with the time you need to wake up. BOTH works backward from age-based sleep-duration guidance instead of promising a perfect wake-up point from fixed 90-minute cycles.
Be asleep by
11:00 PM
A practical planning point
Be asleep by
12:00 AM
CDC/AASM adult consensus reference
The optional buffer is your own estimate for winding down and falling asleep; it is not a medical recommendation. The calculated times are planning references, not guarantees about sleep quality or sleep-stage timing.
Duration guidance before cycle math
Adults 18–60: at least 7 hours
CDC lists 7 or more hours per day for adults ages 18–60. The joint American Academy of Sleep Medicine and Sleep Research Society consensus also recommends 7 or more hours per night on a regular basis for healthy adults in this age range. The calculator shows 7 hours as the minimum reference plus 8- and 9-hour planning examples so you can work backward from your wake time.
Adults 61–64: 7–9 hours
CDC lists 7–9 hours for adults ages 61–64. The calculator shows the lower end, midpoint, and upper end of that range.
Adults 65 and older: 7–8 hours
CDC lists 7–8 hours for adults ages 65 and older. The calculator works backward from your wake time for both ends of that range.
Sleep cycles are real. Exact cycle math is not.
Normal sleep moves through NREM and REM stages in repeating cycles, but published descriptions place those cycles across a range rather than at one exact length. One review describes sleep-stage cycles spanning roughly 60 to 120 minutes. Another describes typical NREM/REM intervals around 90 to 110 minutes. Cycle composition also changes across the night. That makes a calculator that promises a perfect wake-up point from repeated 90-minute blocks more precise than the physiology supports.
A more defensible use of a calculator is to protect enough total sleep opportunity, keep timing reasonably consistent, and then judge the routine by how you sleep and function over time.
Sleep hygiene and basics
Schedule, light, caffeine, bedroom conditions, and when habit advice is not enough.
Sleep trackers and smart rings
What wearables estimate well, where they miss, and how to use trends without overreading a score.
Magnesium glycinate for sleep
What the latest trial found and why the broader evidence still remains uncertain.
Primary references
- CDC: About Sleep, including adult sleep-duration recommendations by age
- AASM and Sleep Research Society: adult sleep-duration consensus statement
- Neurophysiology review: sleep stages can cycle across roughly 60–120 minutes
- Sleep architecture review: NREM/REM intervals commonly described around 90–110 minutes
General education only. This calculator does not diagnose insomnia, sleep apnea, circadian-rhythm disorders, or other sleep conditions. Persistent sleep problems, major daytime sleepiness, breathing concerns, or other significant symptoms warrant qualified evaluation.