• Welcome to Phoenix Rising!

    Created in 2008, Phoenix Rising is the largest and oldest forum dedicated to furthering the understanding of and finding treatments for complex chronic illnesses such as chronic fatigue syndrome (ME/CFS), fibromyalgia (FM), long COVID, postural orthostatic tachycardia syndrome (POTS), mast cell activation syndrome (MCAS), and allied diseases.

    To register, simply click the Register button at the top right.

How soon does PEM hit after exertion?

How soon does PEM hit after exertion?

  • Total voters

Rufous McKinney

Senior Member
Cognitive exertion - especially talking/chatting with others...I get a rapid onset loss of energy and am almost in a coma, plus the strep level sore throat from using the voice.

But other PEM mostly seems to come on the next day. Lasts 48 hours typically...

using my eyes to see - like when I tried to paint...(for less than 30 minutes) I crashed the next day every time....

Nord Wolf

The Northman
New England
Physical or cognitive exertion instigates PEM the same day for me. If I overdo something a little, PEM sets in within 3 hours. If I overdo something a bit more than a little, PEM usually sets in within 1 hour. Though I have "rolling PEM", so it never really ends. The marker is if the ongoing symptoms suddenly increase.
However, if I have a night terror or ptsd episode while sleeping (which I always wake up from), PEM typically sets in immediately.