Letter How much sleep apnea is too much? Authors' response

Our study [1] had two main purposes: first, to examine the occurrence of sleep-disordered breathing (SDB) in patients with chronic fatigue syndrome (CFS), and then to exclude patients with this confound in order to evaluate the structure of sleep in a group of patients with “pure” CFS to look for relations with the symptoms of fatigue and sleepiness. In order to do this, we had to define an upper limit for the