Okay so I had a bit of a relapse, PEM, symptom exacerbation, you get the story... My last big relapse happened in maybe March/April this year, since then i've had a tons of bad-ish days but pacing has allowed me to avoid any major crashes and do quite a lot considering. Anyway...I threw caution to the wind and went on a family holiday abroad last week, I had to be up at 2:30am to travel via car to an airport 90 mins away and get a flight at 6:30am ish. The journey was pretty hellish but aside from being absolutely exhausted on the first day, astonishingly, I recovered well and averaged 2-3 miles of walking per day. I climbed quite a lot of steps, went out on a boat, paddle boarded for 30 mins (with rests), did some light swimming most days (maybe 150-200m max) and stayed up socialising until around midnight each night. I had to make tons of accommodations to do this...lying down a lot, resting a lot, loading up on carbs, fruits, water etc every few hours. On the final day I made a fatal error...I'd been out on a pedalo boat with some of my family in the morning just after breakfast, we were on the boat for around 60 mins, I did some light swimming. After we got off the boat I saw an amazing snorkelling spot and decided to go for another swim...BAM big mistake, despite resting a bit between each swim, I noticed that my brain started to slowly fade into mush, I was becoming lethargic and my breathing was more laboured...I woke up with PEM, exhausted, pain in legs etc and the journey home was a bit of a nightmare to say the least. Fortunately my family helped me pretty much everything on the way back otherwise i'd have been considerably worse. Below are a few observations i've made about the relapse when compared to my other relapses: In all of my relapses I was doing something physical e.g exercise, it also usually involved using my arms. Some of the relapses seem to correspond to overdoing it when it feels like my blood sugar/glucose supply is low or depleted. According to Wiki, the brain is dependent on a continual supply of glucose diffusing from the blood into the interstitial tissue within the central nervous system and into the neurons themselves. This could explain why my brain seems to always be the first thing that turns to mush when i'm approaching my limit/relapse threshold. Taking in glucose more regularly e.g every hour (via lucazade sport, fruit or carbs) in combination with pacing seems to help me avoid these dips and maintain a slightly better baseline. According to a study that Maureen Hanson talked about in her OMF Syposium presentation, plasma glucose is lower in ME/CFS patients, and endurance athletes with higher plasma glucose usually recover better. Question: What thing/s could be affecting glucose utilisation/absorption in this way?