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, including those living with, or still waiting on answers about:
- PMOS, formerly PCOS
- Endometriosis
- Adenomyosis and fibroids
- PMDD
- Thyroid changes
- Low iron
- Perimenopause
- Cycles without ovulation
Reyha is not a diagnosis and not contraception. It keeps a record of what your body actually did, with the number of cycles behind every pattern, so you have something to take to your GP.
1 in 8
women have PMOS. Up to 70% of them do not know it.
9y 4m
the average wait for an endometriosis diagnosis in the UK.
39%
saw their GP ten times or more before it was suspected.
WHO and The Lancet, 2026 · Endometriosis UK, 2026
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
The first fifty
get a year.
The founding offer
Premium free for your first year.
The first 50 people on this list get Reyha premium at no cost for a full year from launch. No card now, nothing to cancel. Just an email address, and a say in what we build next.
No spam. A note the day Reyha reaches the App Store, and the occasional update while we build. Unsubscribe whenever you like.
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