Sleep Calculator
Determine the best time to wake up or go to sleep based on sleep cycles.
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Recommended Bedtimes
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Find Your Perfect Bedtime or Wake-up Time
Our Sleep Calculator helps you determine the best time to go to bed or wake up by working backward in 90-minute sleep cycles, so you can wake up feeling refreshed and energized.
What is a Sleep Calculator?
A Sleep Calculator is a tool designed to help you align your sleep schedule with your body's natural sleep cycles. Based on the principle that a typical human sleep cycle lasts about 90 minutes, it calculates optimal bedtimes if you know when you want to wake up, or optimal wake-up times if you know when you want to go to bed. The goal is to avoid waking up in the middle of a deep sleep cycle, which can leave you feeling tired and groggy.
How It Works: The 90-Minute Cycle
The calculator uses simple time-based arithmetic:
Bedtime = Wake-up Time - (Number of Cycles × 90 minutes) - Time to Fall Asleep
Wake-up Time = Bedtime + (Number of Cycles × 90 minutes) + Time to Fall Asleep
It typically calculates times for 4, 5, or 6 full sleep cycles, corresponding to 6, 7.5, or 9 hours of sleep.
Frequently Asked Questions
How does a sleep calculator work?
A sleep calculator works by using the principle of sleep cycles. An average sleep cycle lasts about 90 minutes. Waking up at the end of a cycle, rather than in the middle of one, can help you feel more rested and less groggy. Our calculator determines ideal bedtimes or wake-up times by counting backward or forward in 90-minute increments.
How much sleep do I need?
Most adults need 7-9 hours of sleep per night to feel rested and function optimally. This typically corresponds to completing 5 or 6 full 90-minute sleep cycles.
What is a sleep cycle?
A sleep cycle is the progression through different stages of sleep, from light sleep to deep sleep and REM (Rapid Eye Movement) sleep. Each full cycle lasts approximately 90 minutes. Waking up during a deep sleep stage can cause sleep inertia, or grogginess.
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