This is about the way many tiny things we may not be paying attention to can add up to cause a crash (PENE/Post Exertional Neuroimmune Exhaustion/PEM/Post Exertional Malaise)

When you realize that the physical, sensory, emotional, and mental things together might have been too much you may be able to save yourself a crash through Aggressive Resting (see video here:    • Aggressive Resting to prevent crashes...  )

My main resource website: cfs-me-navigator.com

Let me also add a list of things that can make PEM happen (alone or together depending on the intensity of the thing and the severity of the person with ME/CFS:

Physical Exertion including exercise, but really anything including just using your arms while in bed.

*I would also add that at certain levels digesting food can be a physical challenge and wear you out. More water/wet foods are easier to digest. Warm foods are easier to digest. Small amounts of food are easier to digest. Large meals, especially cold ones will take a lot of energy.

Sensory: light, strobing lights, sounds, smells, hot/cold, motion, watching motion, screens
Mental: reading, listening to audiobooks or podcasts, conversations, mental/intellectual exercise of any kind

Emotional: stress, worry, excitement, anxiety, depression, anticipation, even too much euphoria that gets you too keyed up

Medical: viral infection, cold, mold exposure, chemical exposure