Delayed post-exertional malaise (PEM): can it be caused by mental over-exertion alone? I’m sure this question is a common one! I’m trying to improve my understanding of PEM from mental and/or physical activity, as I’m currently really struggling, despite having suffered with ME for 20 years! I’m looking to learn from the experiences of others who have experienced severe ME symptoms. Up until last year I have had a relapsing/remitting form of ME. I was working full-time until October 2014 having been free of severe ME symptoms for 3 years. I had a very bad relapse in October 2014. I have been having problems establishing a safe baseline of activity over the last 3 months. I have deteriorated over that time overall to a level of functioning far below anything previously experienced, and am attempting to establish what, if anything, might be preventing me from stabilising my condition. I believe I am a 1-2 on the Activity Scale currently. My ME is primarily neurological – the worst symptoms being crippling nausea, strange “inside head” symptoms (buzzing swarm of bees type feeling in head), tinnitus, bad brain fog, poisoned feeling, temperature dysregulation, bad night sweats, cold feet, muscle tremor and obviously fatigue/exhaustion. Muscle symptoms are bad but bearable – pain and weakness. At present I am experiencing a cyclical pattern, whereby I get a sequence of 3-4 OK days (where OK means I can get up, get dressed, go to the loo, make a cup of tea, read, watch DVD/TV, maybe have a wash/shower) followed by 3-4 very bad days when I struggle to function. One cycle follows another repeatedly. On the OK days I have probably previously over-exerted myself physically by doing physical activity beyond my current capability e.g. tiny bit of household cleaning, having a shower and/or cooking a simple meal. On the bad days I am able to make it to the sofa and watch a bit of TV and spend some time on the laptop, but do no other physical activity. I am able to spend significant time on the laptop or watch TV, even on bad days. I don’t get any immediate increased symptoms, though sometimes it’s difficult to concentrate for a long period. But maybe this is causing me more harm than I am aware of, and contributing to my lack of stability. If you don’t get PEM straight away, what are the signs of overexertion? Have others had experience of delayed PEM as a result of mental activity? Can it be possible that something can be done comfortably that is in reality very harmful? Do you get the same symptoms from overdoing it physically and mentally or are the symptoms noticeably different? What helps? Thanks very much for any guidance/support.