The influence of obesity on sleep quality in male sleep apnea patients before and during therapy.

Evidence exists that obesity, even in the absence of sleep related respiratory disorders, affects sleep negatively. In this study we examined the influence of obesity on sleep quality of male sleep apnea patients before and after breathing normalization with continuous positive airway pressure (CPAP). We compared the polysomnography from the diagnostic night, second night with CPAP, and a control night (three months later) in 13 non-obese, 13 obese, and 12 severely obese male obstructive sleep apnea patients. In the diagnostic polysomnography, obese and severely obese subjects showed increases in apnea-hypopnea index (AHI) and NREM-1 sleep, and decreases in min SaO(2), REM sleep, and partially slow wave sleep (SWS), when compared with the non-obese group. In the second night under CPAP, normalization of the AHI and a rebound of REM and SWS occurred, which was more pronounced in severely obese than in the non-obese and obese group. The polysomnography recorded three months thereafter revealed no differences in sleep stages between the groups. We conclude that after the long-term CPAP therapy, no effect of obesity on sleep quality is apparent.