REMtime - Sleep Cycle Timer

REMtime - Sleep Cycle Calculator

What time should you go to bed tonight to wake up feeling refreshed?
Get the answer instantly and set your alarm right away.

REMtime calculates optimal bedtime and wake-up times based on 90-minute sleep cycle science. It helps you wake up during light sleep stages instead of deep sleep, so you feel more refreshed even with the same amount of sleep.

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Key Features
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Reverse Calculation (Wake-up Time Based)
- Enter your wake-up time and get 4-6 recommended bedtimes
- See cycle count and total sleep duration at a glance

Forward Calculation (Bedtime Based)
- Enter when you plan to sleep and get optimal wake-up times
- Recommended wake-up times for each sleep cycle

"Sleep Now" Button
- Instantly calculate optimal wake-up times from the current time
- Sleep onset latency automatically factored in

Alarm Auto-Set
- Tap a recommended time to instantly set a system alarm
- From calculation to alarm in just one tap

Customizable Sleep Cycles
- Cycle length: Default 90 min, adjustable from 70 to 120 min
- Sleep onset time: Default 15 min, adjustable from 5 to 30 min
- Find your own personal sleep cycle

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App Highlights
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- Beautiful night sky design
- Dark mode by default (easy on the eyes at night)
- Available in Korean and English
- Lightweight and fast
- Works offline
- Personalized cycle length and sleep onset settings

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The Science Behind It
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Sleep consists of alternating NREM and REM stages in roughly 90-minute cycles. Waking during deep sleep (N3) causes sleep inertia - that groggy, exhausted feeling. Waking at the end of a cycle during light sleep means feeling more refreshed with the same total sleep time.

REMtime uses this principle to calculate when sleep cycles end, so your alarm goes off at the optimal moment.

Note: 90 minutes is an average estimate - actual cycles vary between 70-130 minutes per person. REMtime honestly communicates these limitations and lets you customize your cycle length.

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Supported Languages
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Korean, English

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Contact & Feedback
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Have suggestions or ideas for improvement? We'd love to hear from you!

Email: [email protected]