Cycle intelligence · London
Your cycle doesn't follow the textbook.
Reyha doesn't either.
If your cycle is irregular, unpredictable or painful, a calendar app guesses, and gets it wrong again. Reyha reads what your wearable already knows: temperature, resting heart rate, HRV and sleep. It works from your own body rather than a 28-day template, and it won't tell you where you are in your cycle until your own signals show it.
Built for the cycles other apps get wrong
You have been told your bloods are normal. Your app has predicted your period wrong three months running. The pain started before your period again, and you have been keeping a diary for two years.
Reyha is built for you: women whose cycles are irregular, unpredictable or painful, whatever's behind it, and whether or not anyone has put a name to it yet. If any of this sounds like yours, it was built with you in mind:
- Cycles that run 26 days, then 45
- Periods that disappear for months
- Pain that starts before your period, or never fully leaves
- Bleeding heavy enough to plan your week around
- Mood that drops away in the days before your period
- A cycle that's changing in your forties
- Coming off contraception and meeting your own cycle for the first time
- A diary you've kept for years
Reyha isn't a diagnosis and it isn't contraception. It keeps a record of what your body actually did, with the number of cycles behind every pattern, so your next GP appointment starts from what happened rather than what you can remember. It won't diagnose you. It'll help you be believed.
13%
of 612,613 real cycles were 28 days long. The textbook cycle is the exception.
Day 10 to 30
the range ovulation fell across in those cycles. Day 14 is a textbook figure, not a rule.
Bull et al., npj Digital Medicine, 2019
What it actually does
I · Reads
Your wearable, already on your wrist.
Apple Health or Health Connect. Temperature, resting heart rate, HRV and sleep: the signals that shift with your cycle, read against your own baseline rather than a population average.
II · Decides
Four calls a day, not a wall of charts.
Eat, train, sleep, and one that changes with the phase. Each one is a single sentence you can act on before you've finished your coffee.
III · Explains
The mechanism, never the horoscope.
Every line opens into the physiology behind it. Where the evidence is thin, Reyha says so. Where it can't know yet, it hedges instead of guessing.
A 28-day template is not your cycle. It is an average you were handed.
Millions of women wear a device that measures temperature, heart rate and sleep every night, and have a cycle that moves all three. Almost nothing joins the two up, and the apps that try assume a regular cycle. Reyha is built for the women that assumption fails, and it shows its working.
The colour is the phase
See it work
The explainer · Two minutes
06 · Founding 50
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