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Sensitive opt-in

Cycle tracking is opt-in, private and free.

Turn on cycle tracking to see period days next to your sleep and recovery. It does not change your Life Index, and it stays on your iPhone.

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The question

Start with what your own data can show.

Many people want wearable data read alongside their cycle, because HRV, temperature, sleep and energy can shift across the month.

Cycle tracking is free and off until you turn it on. daygauge treats it as sensitive: it stays on your phone and does not guess at your hormones or health.

Quick answer

Once you turn cycle tracking on, daygauge shows period days on a cycle card in Today, next to sleep, resting heart rate, HRV and wrist temperature from Apple Health.

Questions answered

What this guide covers.

  • Can cycle phase affect HRV?
  • Can wearables show menstrual patterns?
  • Does cycle data change my Life Index?
  • How does daygauge keep cycle data private?
  • Can daygauge predict fertility?
In daygauge

How the app handles this.

Signal
You add period days by hand, from Apple Health menstrual flow, or from a Clue or Flo export. Fertile-window and ovulation dates are optional calendar estimates, off by default. They are not contraception, pregnancy or medical advice.
Confidence
Missing readings lower confidence instead of creating false certainty.When a reading is not available, daygauge says so rather than filling the gap.
Weekly Review
Weekly Review shows what changed, what held and what to try next.Your first Weekly Review is free. Later reviews are part of Pro.
Illustrative example

What this can look like in the app.

Cycle card: day 21, with your resting heart rate and HRV shown beside it.

Example
Confidence

A pattern is only called proven after it repeats on your own paired days. Missing readings lower confidence.

Next move

Try one small change, log it in Quick Log, then compare your next readings.

Example 1

Sleep: in the days before your period you averaged 34 minutes less sleep than in the first half of your cycle.

Example 2

Privacy: cycle data stays on your iPhone and does not change your Life Index.

Research

Further reading.

These studies describe groups of people. They help explain the topic, but they cannot tell you what will happen to you.

Research context only. daygauge does not diagnose, treat, prevent or predict disease risk. Personal medical concerns belong with a qualified clinician.

Limits

What daygauge does not do.

  • It does not diagnose, treat or prevent disease, or predict your risk of it.
  • It does not claim one habit caused a result. It shows the pattern, how confident it is and what else changed.
Read next

Related guides.

Endocrine disruptors: what the research says and what an app cannot tell youWearables can show stress proxies. They cannot read your mindPrivacy notice
On the App Store

Want to see your cycle next to your sleep and recovery?

daygauge is free to download. Pro is £8.99 a month or £49.99 a year.

Download on the App Store

Personal analytics, not medical advice