How does the sleep cycle calculator work?

The calculator uses the science of 90-minute sleep cycles. A full sleep cycle takes about 90 minutes, and waking up between cycles (rather than mid-cycle) helps you feel more refreshed. The tool calculates optimal wake-up or bedtime based on completing full cycles.

What is the 90-minute sleep cycle?

During sleep, your body cycles through light sleep, deep sleep, and REM sleep. One complete cycle takes about 90 minutes. Most adults need 4-6 complete cycles (6-9 hours) per night for optimal rest.

Why does it add 14 minutes to fall asleep?

Research shows the average adult takes about 14 minutes to fall asleep. The calculator factors this in so your actual sleep cycles align with the suggested times.

How many sleep cycles do I need?

Most adults need 5-6 sleep cycles (7.5-9 hours) for optimal health. The tool shows options for 4-6 cycles, with the "Best" badge on the option with the most cycles.

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睡眠計算器

睡眠計算器

根據 90 分鐘的睡眠週期，計算最佳的就寢時間或起床時間。最佳化您的睡眠排程，以獲得更好的休息和更多的精力。

Select your wake-up time

Select a Time

Choose your target wake-up or bedtime above, and we'll calculate the best times based on natural 90-minute sleep cycles.

使用方式

選擇模式

選擇您是要計算起床時間還是入睡時間。

設定時間

輸入您的目標起床時間或計畫入睡時間。

檢視推薦

根據90分鐘睡眠週期取得最佳時間推薦。

關於此工具

根據 90 分鐘的睡眠週期，計算最佳的就寢時間或起床時間。最佳化您的睡眠排程，以獲得更好的休息和更多的精力。

Wake up feeling refreshed by aligning your sleep schedule with natural 90-minute sleep cycles. Our calculator finds the optimal bedtime or wake-up time so you never wake up mid-cycle again.

All data is stored locally in your browser and never uploaded to any server. No registration required.

90-Minute Cycle Science

Calculations are based on the natural 90-minute sleep cycle so you wake up between cycles, not mid-cycle.

Dual Mode — Wake Up or Fall Asleep

Choose whether you want to find the ideal bedtime or the best wake-up time based on your schedule.

Fall-Asleep Adjustment

A built-in 14-minute buffer accounts for the average time it takes to fall asleep, keeping your cycles accurate.

瞭解更多

Better Wake-Up Timing — Set your alarm for the end of a sleep cycle so you wake up feeling refreshed instead of groggy.

Shift Work Scheduling — Quickly find the best sleep window when your work hours change from day to night.

Jet Lag Recovery — Adjust your bedtime gradually across time zones by calculating optimal sleep and wake times.

睡眠計算器

推薦時間

Understanding Sleep Cycles