Circadian Rhythm Calculator

Calculator Inputs

Target wake time

Desired sleep duration (hours)

Chronotype

Sleep debt (hours)

First bright light time

Bright light duration (minutes)

First meal time

Current caffeine cutoff

Exercise time

Routine consistency (%)

Age group

Work style

Plotly Graph

The chart shows how your daily timing anchors align across the day. Higher points reflect stronger alertness or activity periods.

Example Data Table

Profile	Wake Time	Sleep Need	Chronotype	Sleep Debt	Suggested Bedtime	Peak Focus 1
Office Worker	6:30 AM	8h 0m	Intermediate	1.0h	10:00 PM	9:00 AM - 11:30 AM
Student	7:15 AM	8h 30m	Late	2.0h	11:20 PM	9:45 AM - 12:15 PM
Older Adult	5:45 AM	7h 30m	Early	0.5h	9:10 PM	8:15 AM - 10:45 AM

Formula Used

1. Target sleep opportunity: Desired sleep duration + sleep debt adjustment.

2. Suggested bedtime: Wake time - target sleep opportunity + chronotype shift + age adjustment + work schedule adjustment.

3. Melatonin-friendly window: Suggested bedtime - 90 to 45 minutes.

4. Focus windows: Wake time + 150 minutes for the first block, then another block around nine hours after waking.

5. Recommended caffeine cutoff: Suggested bedtime - 9 hours.

6. Phase alignment score: 100 - penalties for delayed light, meal timing, late caffeine, exercise mismatch, and poor routine consistency.

This calculator offers planning estimates only. It does not diagnose sleep disorders or replace professional medical care.

How to Use This Calculator

Enter your normal wake time and preferred sleep duration.
Select the chronotype that best matches your natural tendency.
Add your current sleep debt, first light time, and first meal time.
Enter caffeine cutoff, exercise time, and routine consistency level.
Click the calculate button to generate your timing plan.
Review the result cards above the form for bedtime, focus windows, and timing anchors.
Use the CSV or PDF buttons to save the result summary.

Frequently Asked Questions

1. What does this calculator estimate?

It estimates bedtime, wake window, focus periods, nap timing, exercise timing, and a simple alignment score using your daily routine and sleep preferences.

2. Is this a medical diagnosis tool?

No. It is a planning tool for daily habits. Persistent insomnia, severe fatigue, breathing issues, or major schedule disruption should be discussed with a qualified clinician.

3. Why does chronotype change my bedtime?

Earlier chronotypes usually feel sleepy sooner. Later chronotypes often become alert later. The calculator shifts bedtime estimates to reflect those common timing differences.

4. Why is bright light important?

Morning bright light is a major time cue for the body clock. Good timing may help reinforce alertness earlier in the day and improve schedule consistency.

5. How should I interpret the phase alignment score?

Higher scores suggest your routine cues line up better with the suggested schedule. Lower scores suggest more mismatch from light, meals, caffeine, exercise, or irregular timing.

6. Can shift workers use this tool?

Yes, but results are more approximate. Shift schedules can strongly affect circadian timing, so the schedule adjustment provides direction rather than a precise clinical recommendation.

7. Does sleep debt change the recommendation?

Yes. More sleep debt increases target sleep opportunity, which usually moves the suggested bedtime earlier and can affect the timing of other daily anchors.

8. What should I export with CSV or PDF?

Exporting saves your calculated schedule summary. That makes it easier to compare routines over time, share notes, or keep a wellness planning record.