Some days are foggy.
Find out why.
FoggyBrain is a gentle iPhone app that connects your brain fog to sleep, stress, food, and weather — and shows you what actually helps.
Free to use. No account. Your data stays yours.
Three small habits. One clearer head.
1
Log in two taps
Rate your fog when you think of it — from the app, a widget, or your Lock Screen. It takes seconds, on purpose.
2
Let patterns emerge
FoggyBrain quietly lines your ratings up against sleep, stress, sugar, exercise, cycle, and even the weather.
3
See what helps
After a couple of weeks, your triggers stop being a mystery. Bring the report to your doctor, or just to yourself.
Why this app exists
Built by someone who lived in the fog
FoggyBrain wasn't designed in a boardroom. It was built during a long COVID recovery, by someone who needed it — and couldn't find it.
Read our story
Now on the App Store
Start tracking today
FoggyBrain is free to download for iPhone. No account. Your data stays on your device.
Understand your fog
All articles
Tracking
How to track brain fog: a simple method that works
A low-effort way to log brain fog, what to record alongside it, and how to spot your triggers in a few weeks
6 min read
Understanding
Brain fog and ME/CFS: crashes, pacing, and finding your limits
Why brain fog is a core symptom of ME/CFS, how post-exertional malaise makes it worse, and how pacing and tracking can help
7 min read
Lifestyle
Brain fog after eating: why it happens and what helps
Why some meals leave you foggy, sluggish, or sleepy, and how to find out which foods affect you
6 min read
Private by design
No account. No ads. No trackers. Your data lives on your iPhone and in your own iCloud — never on our servers, because we don't have any. Even the AI insights run entirely on your device.
Read the privacy policy