So first of all, let's describe what I am talking about. Basically, I've noticed this pattern: The deeper and longer I sleep the worse I will feel. If I have poor / broken sleep or sleep for a very short time (< 5 hours) my symptoms are greatly reduced. When I sleep well or long I get symptoms like: increased fatigue, arm weakness and pain, diziness, sleepiness (paradoxically enough), etc. If I sleep bad, many of those are eliminated or greatly reduced. On a few occasions, when I had slept for only 2-3 hours I even had a remission like feeling for an hour or two! The obvious question is, why dont you sleep 5 hours every day then? Once I've fallen into a deep sleep it's extremely difficult to wake up. So even if I set my alarm 5 hours after bed time, the urge to continue sleeping will be too great and I might just turn it off. Even if I somehow manage to get up, I would be so sleepy that after an hour or two I would give up and go back to bed. If I sleep lightly / badly then this becomes much easier, unfortunately I have no control over, whether I sleep deeply or lightly during the night. Interestingly, this all started 2 years ago, after a severe crash, before that I always had unbroken 9-10 hour long sleep, which didnt correlate with symptoms. I've heard of quite a few other people who have the exact same symptom. Which seems very intriguing. Considering how specific and rare this symptom is, it could possibily provide insights into the disease process behind CFS/ME for some sub-group of patients. I did some research to see if this symptom occurs in other illnesses, but couldn't find much. One thing popped up though: sleep deprivation therapy seems to be very effective in curing depression! I am pretty sure this doesn't apply to me though, considering the plethora of neurological symptoms I have (arm and muscle weakness, parasthesias, POTS, diziness, overactive bladder, etc.), which rarely or never occur in depression. Does anyone else have this symptom? And does anyone have a hypothesis, behind what causes it? I have a hypothesis of my own, which is related to the findings of mr. Younger. He found increased neuroinflamation in ME/CFS patients. My hypothesis is that, deep sleep somehow further increases neuroinflamation, thus making symptoms worse. I feel that, if many other patients have this symptom, a study would be warranted. There are many things that could be researched, among others: first of all confirm that sleep deprivation indeed improves symptoms, then measure levels of neuroinflamation, see if it correlates with deep sleep, then measure other variables to see how sleep deprivation affects them, etc.