What is Sleep cycle bedtime calculator for?

Calculate bedtime windows from wake time, age band and wind-down time. It helps turn bedroom light, screen timing, temperature, humidity or routine clues into one practical next action.

Is this medical advice?

No. Drift Light pages are practical bedroom-environment guides. They do not diagnose, treat or measure medical sleep problems.

What should I change first?

Change one visible bedroom cue first, such as late bright light, close screen use, room heat, damp air or airflow. Keep the rest of the routine stable for a night or two so the result is easier to read.

Bedroom sleep tool

Sleep cycle bedtime calculator

Calculate bedtime windows from wake time, age band and wind-down time.

All tools

Practical output.

Use the result as a room test, not as a diagnosis.

Enter your room details

How to use this result

Many bedtime calculators stop at ninety-minute cycles. Drift Light adds the missing room step: when the warm-light routine should start before the chosen bedtime window.

The calculator offers several practical windows rather than pretending there is one perfect minute. Pick the window that you can repeat on ordinary nights, then protect the final wind-down period.

Cycle timing is an approximation. Real sleep has variation, awakenings and different needs by person.

Best use

Run the tool, choose one change, repeat it for two or three nights, then compare the room notes. A repeated pattern is more useful than one perfect-looking number.

Next useful pages

ToolBedtime light routine builderBuild a practical evening light routine from bedtime, screens and lamp type.

ToolBlue light evening exposure estimatorEstimate evening screen and room-light load before bed, then choose the first reduction step.

ToolBedroom sleep temperature plannerCompare bedtime and morning temperature patterns and choose one room change to test.

ToolBedroom humidity and condensation checkerUse room temperature, RH and window clues to judge next-night condensation risk.

evening lightBedroom light for sleep: a practical evening setupHow to shape bedroom light before bed with warm lamps, screen boundaries and a simple fade.

screensEvening blue light and screens before bedA practical guide to close screens, bright rooms and the last hour before sleep.

humidityBedroom condensation and sleep comfortWhy windows mist overnight and how humidity, ventilation and temperature interact.