Q: I wake up each morning feeling tired, even though I have slept. Would a sleep study be useful?
A: There are at least four core symptoms in ME/CFS: pain, cognitive dysfunction, fatigue or post-exertional malaise, and non-restorative sleep. Thus, awakening unrefreshed is one of the cardinal symptoms of ME/CFS, and one of the last symptoms to resolve as one improves. You will probably wake up tired whether you sleep 4 hours or 14.
Nevertheless, primary sleep disorders such as apnea and periodic leg movements occur in up to 60% of people with ME/CFS or FM, and can disrupt sleep. So, if such problems are suspected, then a sleep study would be in order.