What to track
The signals that matter most in ME/CFS are ones that can warn of a crash a day or two before it hits, or flag an infection early:
- Overnight heart rate variability (HRV). A drop often comes before PEM.
- Resting heart rate. A rise can signal over-exertion or illness.
- Respiratory rate and skin temperature. Useful for spotting infections early.
- Sleep
- Real-time heart rate during activity. This is the key pacing tool.
A simple daily log
You don’t need a device. Each night, record:
- Energy today (0–10)
- Brain fog today (0–10)
- Crash? (yes/no)
- What I did. A few words.
- Sleep quality
- Changes. Any new supplement, medication or dose, with the date.
After 4–8 weeks, compare weekly averages. You’ll start to see which activities cost the most and whether any treatment is helping. It’s also powerful evidence to show a doctor.
Devices compared
Prices are in Australian dollars as at September 2026 and change often.
| Device | Price (AUD) | Good for ME/CFS | Watch out for |
|---|---|---|---|
| Visible app + Polar armband | Paid tier includes armband | Built for ME/CFS and Long COVID pacing. Real-time heart rate alerts, a daily “PacePoints” energy budget, HRV, symptom and medication tracking, monthly reports for doctors, optional research participation. | Armband form factor |
| Garmin Cirqa (screenless band, launched July 2026) | ~$300, no subscription | “Body Battery” and stress tracking are widely used for pacing in the ME/CFS community. Up to ~10 days of battery. Accurate heart rate in reviews. | The Garmin Connect app is dense, which is hard on brain-fog days. New product. |
| Whoop 5.0 | Membership only; renewals ~$299–$629/year after year one | Mature HRV and recovery tracking; comfortable to wear 24/7 | No ME/CFS mode. Its “Strain/Recovery” model assumes an athlete, so a “green” day prompts you to push harder. No PEM concept or real-time stop alert. |
| Google Fitbit Air | ~$199; Premium $14.99/month or $99.99/year | Cheapest option. Light, ~1 week of battery, good sleep tracking, SpO₂, HRV, breathing rate, skin temperature | Limited without Premium. The AI coach sets activity goals that may not suit pacing. |
Before you buy, check it has
- Real-time high heart rate alerts during activity. The single most useful feature.
- Overnight SpO₂ (blood oxygen). Not diagnostic, but trends can support a request for a sleep study.
- A simple app you can use on a foggy day
Signs a treatment might be working
When something helps in ME/CFS, it usually shows up in your data a week or two before you notice it:
- Resting heart rate trending down a few beats
- Morning HRV trending up
- Fewer over-limit days at the same activity level
- Fewer and shorter crashes