Invisible illness, made visible.
The crashes don't come out of nowhere. The body sends signals — HRV, resting heart rate, sleep architecture, skin temperature — for days before. Belle Ring catches them, gives you a pacing budget that holds, and produces the chart your doctor will actually read.
Subjective experience. Objective trend.
Most chronic conditions are diagnosed by what you say. That makes appointments harder than they should be. Belle gives you the second voice in the room — your own physiology, recorded continuously, no memory required.
"On a scale of one to ten, how would you rate your fatigue today, in general, on average, over the last month?"
"Here's a 90-day chart. Resting HR climbed 8bpm in the week before each crash. Three crashes. Same pattern."
Stop second-guessing. Start seeing the pattern.
Built for the bodies medicine still under-listens to.
Not a substitute for diagnosis or care. But a reliable set of signals — paired, in your case, with an honest cycle layer — that often catches what a quarterly appointment can't.
Belle's pacing engine is anchored in HRV-driven heart rate ceilings — the validated approach for avoiding PEM crashes. Your phone learns your safe zone over 14 days and tells you when you've stepped outside it.
Resting heart rate elevation and sleep fragmentation are two of the most consistent post-COVID signals. The ring catches a relapse 3–5 days before subjective fatigue reports it.
Sleep stages — particularly deep sleep collapse — predict next-day pain better than activity load alone. Belle pairs sleep architecture with cycle phase so you stop blaming yourself for the bad weeks.
Resting heart rate and skin temperature are sensitive to thyroid swings between blood draws. The ring helps explain why you felt different two months apart on the same TSH.
Flares often track HRV decline 5–7 days ahead. For premenopausal users, late-luteal flare risk is real — Belle is one of the few tools that show both the cycle and the autoimmune pattern on one chart.
Sleep disruption + pre-menstrual estrogen drop is the classic menstrual-migraine signature. Belle flags the prodrome window so you can pre-medicate, hydrate, and lower stimulus.
Autonomic disruption (HRV) and sleep fragmentation predict IBD flares; cycle phase amplifies IBS symptoms predictably. Pair Belle with a simple stool log in the app for the full picture.
Postural tachycardia patterns and cycle-driven joint laxity are both visible in the data. Belle's POTS-aware view shows orthostatic HR change without a tilt table.
When mood is hard to read, sleep + HRV often aren't. We don't replace a clinician — we give you a chart of how your body is actually doing, even on the weeks when self-report fails.
An energy budget that doesn't lie.
Most fitness apps are built for people getting fitter. Belle's pacing engine is built for people staying out of crashes. It learns your safe zone and tells you, gently, when you're about to leave it.
- 1HR-anchored ceilingSet automatically using a 14-day rolling baseline of your HRV. A drop below baseline lowers your ceiling — the day adjusts to the body.
- 2Soft buzz, not panicA gentle vibration at 90% of ceiling. You can dismiss. There's no penalty for going over — just a quieter day suggested tomorrow.
- 3Crash forecast72 hours of over-range, plus a poor sleep night, plus a luteal phase = high crash risk. The app names it before the body does.
- 4Recovery scoring, not productivity"Today, recovery is the work." A score that rewards rest, not steps. Built in collaboration with ME/CFS clinicians and patients.
For most chronic conditions, luteal hits hardest.
Autoimmune flares, migraines, IBS, fibromyalgia pain, ME/CFS crashes — most cycling women report a clear premenstrual peak. We don't think we discovered this. We think it's strange that almost no chronic-illness app accounts for it.
Cycle phase, on the same chart as your symptoms.
Belle Ring shows you the cycle bar on every health view — not just the cycle tab. So when you're staring at a crash on May 18th, you can see at a glance: that was Day 24. The same Day 24 as the last two crashes.
For users on hormonal birth control or in menopause, the cycle layer collapses to a non-cyclical baseline — but stays visible, because steady is also a pattern.
Designed by people who know some weeks the goal is keeping it on.
An app that demands daily logging, gamifies streaks, or shouts at you for 4,000 fewer steps fails on the days it matters most. Ours is built backwards from that fact.
Passive by default. No streaks.
The ring records continuously; the app never punishes you for missing a day. There is no streak counter, no flame emoji, no badge for "active this week." Logging is optional, on your terms.
Quiet mode for crash weeks.
One tap and the app collapses to a single card: today's pacing budget, one suggestion, nothing else. No graphs to interpret, no extra tabs visible. Comes back when you do.
Cycle layer that adapts to your life.
Cycling, on hormonal birth control, peri or post-menopausal, pregnant — the app adapts. The cycle stops being a flat assumption and becomes one of many honest baselines.
A ring that disappears.
Titanium with a smooth PVD finish, 4–6 grams, no lights or ports on the skin side. We send a free sizing kit so you can wear sample rings (resin) for two days each before committing — sensory tolerance matters.
Provider-ready PDFs.
A single tap produces a 30 / 60 / 90-day PDF for your GP, rheumatologist, gynecologist, neurologist or psychiatrist. Cycle aligned, plain language, designed for a 10-minute appointment.
"For ten years my GP wrote 'patient reports tiredness'. After three months with Belle, she wrote 'HRV depression with cyclic worsening, cycle-phase 24+, refer rheumatology.' Same body. Different sentence."
The chart your doctor will actually read.
Most chronic-illness apps export raw CSV or a colorful screen no clinician has time to interpret. Ours is one A4 page, plain-language, cycle-aligned, peer-tested with French and German GPs and specialists. You bring it. They read it. The conversation changes.
