Sleep Calculator
Wake up feeling rested by timing your sleep to align with your natural 90-minute sleep cycles.
Sleep Cycle Stages
- NREM Stage 1 – Light sleep (5 min)
- NREM Stage 2 – Sleep onset, heart rate slows (25 min)
- NREM Stage 3 – Deep sleep, restoration (45 min)
- REM – Dreaming, memory consolidation (15 min)
One full cycle ≈ 90 minutes. Most people need 5–6 cycles (7.5–9 hrs).
Sleep Tips
- Keep a consistent sleep/wake time
- Avoid screens 1 hour before bed
- Keep bedroom cool (65–68°F)
- Avoid caffeine after 2pm
FAQs
Sleep cycles last approximately 90 minutes and include light sleep, deep sleep, and REM (Rapid Eye Movement) stages. Waking up between cycles — rather than in the middle of one — leaves you feeling refreshed instead of groggy.
The CDC recommends 7–9 hours for adults (18–64), 7–8 hours for seniors (65+), and 8–10 hours for teenagers. Consistently sleeping less than 7 hours is associated with increased health risks.
Sleep debt is the cumulative effect of not getting enough sleep. It can't be fully recovered in a single night. Chronically short sleep impairs cognition, mood, immune function, and metabolism.