Blog
Pregnancy, heat, and barometric pressure: what research does and doesn't show
What large studies say about heat during pregnancy, why the research on barometric pressure doesn't hold up, and which symptoms mean it's time to call a doctor, not watch the weather.
Your cycle and the weather: what your own record shows, and what research hasn't measured
The same weather can land differently in different weeks. What's actually established about the menstrual cycle and weather, how little research has measured it, and what your own record can show.
Measuring heart rate with your phone camera: how it works, and how accurate it really is
Camera-based heart rate uses photoplethysmography, the same optical principle as pulse oximeters. Here's the honest picture of what it can and can't estimate.
How much water do you actually need? Weather, activity, and the hydration myths
The "8 glasses a day" myth, what EFSA's actual water guidance says, and why the consensus on fluid intake during exercise points at thirst rather than at drinking more.
VO₂ max, blood oxygen, and breathing rate: what your Apple Watch measures and MeteoHealth shows
Apple Watch measures blood oxygen and estimates breathing rate and VO₂ max; MeteoHealth reads them from Apple Health and shows them next to the weather — it never measures them itself.
Weather and sleep: heat, daylight, and pressure — what the evidence actually shows
Heat and a stuffy bedroom, daylight and your body clock, and barometric pressure: three ways weather might touch your sleep — and, honestly, only two of them hold up under evidence.
Sleep debt: how to actually think about it
Where 'sleep debt' comes from, what chronic sleep restriction research shows, why weekend catch-up sleep falls short, and why your own trend and regularity matter more than an hours-based number.
Wrist temperature during sleep: what Apple Watch is actually tracking
Apple Watch reports a nightly wrist-temperature deviation from your own baseline, not your body temperature. What that signal reflects — cycle, sleep, feeling unwell — and what it doesn't.