Find the optimal time to wake up or go to bed based on natural 90-minute sleep cycles.
Rest Planning
* Includes 15 min buffer to fall asleep
Optimal Bedtimes
Enter your preferred time and we'll calculate the best moments to sleep or wake up based on biology.
About this calculator
Overview
A good night's sleep is essential for physical health, brain function, and emotional well-being. Sleep is not a static state of rest, but a series of ninety-minute cycles that take your body through different stages of repair and recovery. Waking up at the end of a cycle, rather than in the middle of deep sleep, allows you to feel refreshed and alert instead of groggy.
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Pro Tips
Keep your bedroom cool, dark, and quiet to signal rest to your brain.
Avoid blue light (phones) at least 30-60 minutes before bed to allow melatonin production.
Consistency is key—aim for the same wake-up time even on weekends.
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Fun Facts
"Waking up during deep sleep causes 'sleep inertia', the heavy feeling you get when your alarm goes off mid-cycle."
"Humans are the only mammals that willingly delay sleep, often ignoring circadian rhythms."
"Your brain uses sleep to flush out toxic byproducts of neural activity via the glymphatic system."
Formula: 5-6 cycles of 90 minutes each + 15 minutes falling asleep buffer
