Find the best bedtime or wake-up time based on 90-minute sleep cycles. Wake up refreshed, not groggy.
Recommended Times
💡 Tip:
These times assume you fall asleep in about 15 minutes. Try to be in bed 15–20 minutes before your target sleep time.
How to Use
- Choose whether you want to calculate from a wake-up time or a bedtime.
- Enter your desired wake-up time (e.g., 7:00 AM for work) or bedtime.
- Click "Calculate Sleep Times" to see all optimal sleep/wake options.
- Choose the option that gives you the most complete sleep cycles (5 or 6 cycles recommended).
- Plan to be in bed 15–20 minutes before your calculated bedtime.
Features
- Calculates optimal times based on scientifically-backed 90-minute sleep cycles.
- Works both ways: from wake-up time to bedtime, or bedtime to wake-up time.
- Color-coded quality indicators: recommended (green), good (blue), marginal (yellow), poor (red).
- Accounts for average 15-minute sleep onset time for realistic results.
- No account required, no data stored — runs entirely in your browser.
Use Cases
- Setting the perfect alarm time for work or school without feeling groggy.
- Adjusting sleep schedule when traveling across time zones.
- Planning nap times — use 1 cycle (90 min) or just 20 minutes (power nap).
- Building a healthier sleep routine and improving daily energy levels.
- Preparing for an important event — presentation, exam, or early flight.
FAQ
- How does the sleep calculator work?
- Sleep cycles last approximately 90 minutes each. Waking up at the end of a complete cycle — rather than mid-cycle — helps you feel more refreshed. We add 15 minutes for average sleep onset time to give realistic results.
- How many sleep cycles do I need?
- Most adults need 5–6 sleep cycles per night (7.5–9 hours). 6 cycles is ideal; 5 cycles (7.5 hours) works well for many people. Fewer than 4 cycles consistently may impact health and cognitive performance.
- Why do I still feel tired after 8 hours of sleep?
- You may be waking up mid-cycle, causing sleep inertia (grogginess). Try adjusting your alarm to align with a complete cycle endpoint. Our calculator helps you find times to wake at the end of a cycle.
- What is the best time to go to sleep?
- Work backwards from your required wake-up time using 90-minute increments. For a 7:00 AM wake-up, ideal bedtimes are 9:45 PM (6 cycles), 11:15 PM (5 cycles), or 12:45 AM (4 cycles).
- Is it safe to rely on this calculator?
- This calculator is based on sleep science research and is a great starting point. However, individual sleep needs vary. If you have persistent sleep problems, consult a healthcare professional.