PEM — the crash that follows even small efforts — is the defining feature of ME/CFS and a major symptom in Long COVID. Tracking it carefully is one of the most important things you can do to protect your health and communicate what's really happening.
Post-exertional malaise isn't ordinary tiredness. It's a delayed, disproportionate worsening of symptoms that follows physical, cognitive, or emotional effort — sometimes by 12 to 48 hours. The delay is what makes it so dangerous and so hard to explain: by the time the crash hits, you've forgotten what triggered it.
Tracking closes that gap. When you log your energy and activity every day, you can look back two days before a crash and see exactly what happened. That lag time — the distance between effort and consequence — becomes visible in your data. You start to learn your personal threshold before crossing it becomes a multi-day setback.
For people with ME/CFS, pacing is the primary management strategy. But pacing without data is guesswork. Knowing that a 30-minute walk reliably causes a two-day crash — or that cognitive effort on top of poor sleep is your particular trigger — lets you make actual decisions about your energy.
And when you see a new doctor or need to explain your limitations for disability or accommodation purposes, a log showing the clear pattern of exertion and crash is far more persuasive than memory alone. PEM is frequently disbelieved or misunderstood; your data is your advocate.
Note: The Good Tracker does not provide medical guidance on pacing or treatment. If you have ME/CFS or Long COVID, please work with a knowledgeable care provider. Tracking is about building your record — not about going it alone.
Log how you felt before any significant effort. This is your baseline for that day — the starting point that makes the post-crash comparison meaningful.
Note what you did: physical, cognitive, social, or emotional effort. Even a difficult phone call or a stressful conversation counts. Include duration and rough intensity.
Log how you feel 12–24 hours later. The severity of the crash relative to the effort is the core signal. Over time this reveals your personal threshold.
How many days until you felt back to your baseline? Track this across multiple crashes and you'll see patterns — which activities cost the most and how long recovery tends to take.
Rate your worst day in a PEM episode on a 0–10 scale. Comparing severity across crashes helps you identify which triggers produce the worst outcomes.
Unrestorative sleep is common in ME/CFS and compounds PEM. Tracking it alongside crashes shows whether poor sleep makes crashes worse or longer.
The power of PEM tracking is in the before/after comparison. If you only log on bad days, you lose the baseline. A 10-second energy rating every morning builds the picture you need.
The Good Tracker has a dedicated crash/flare toggle. Tap it on any day that feels like a PEM episode. This marks those days visually in your history so you can find the activity logs from 1–2 days before without hunting.
When a crash hits, speak a voice note: "Yesterday I did X, felt Y, now I'm in a crash." The app transcribes and timestamps it. This captures the trigger-to-crash link while it's fresh.
On days two and three after a crash, rate your energy again and note what you were able to do. This builds your personal recovery timeline — crucial for pacing decisions and explaining your condition to others.
Use the Ask tab to generate summaries like "How many crash days did I have last month?" or "What activities appear most often before a crash?" This turns your raw log into something you can hand to a doctor.
Normal fatigue improves with rest. PEM worsens with activity — even modest activity — and rest doesn't reliably resolve it. The hallmark is that the crash is delayed (often 12–48 hours after effort) and disproportionate to the effort expended. Tracking this delay is part of what makes logging so useful for PEM specifically.
Absolutely. Cognitive exertion — focused work, stressful conversations, screen time, emotional events — can trigger PEM just as physical effort does in ME/CFS. Log it the same way: what you did, for how long, and how you felt the next day.
You can scroll back through your full log history at any time. The crash flag makes it easy to find PEM episodes; from there, look at the two days prior to see what preceded them. The Trends view also shows your energy and crash flags on a timeline.
No — that's for your care team. The app records your data and helps you find patterns. How to act on those patterns is a conversation to have with a doctor who understands ME/CFS or Long COVID. What the app gives you is evidence to bring to that conversation.
Free to use. Voice-first. Works even when you're in the middle of a crash.
Open The Good Tracker →