The differences in sleep profile changes under continuous positive airway pressure (CPAP) therapy between non-obese, obese and severely obese sleep apnea patients.

Sleep disturbances in obstructive sleep apnea are caused mainly by repetitive apneas and hypopneas. An alternative factor contributing to disordered sleep may be the obesity, which is frequently associated with sleep apnea. The sleep disturbing effect of obesity was found previously in obese nonapneic subjects. The aim of this study was to evaluate the effect of obesity on sleep quality in sleep apnea patients in particular in patients under continuous positive airway pressure (CPAP) with successfully normalized respiration. We reviewed the archive data of 18 non-obese, 18 obese and 17 severely obese age and gender matched sleep apnea patients treated with CPAP. The polysomnographic parameters from the diagnostic night, from the second night under CPAP and from the follow up night (after three months of CPAP use) were compared. Before CPAP the apnea hypopnea index was worse in obese and in severely obese group and it normalised under CPAP in all groups. The severely obese group showed more light sleep and less REM sleep before CPAP and inversely - less light and more REM sleep in the second night under CPAP than the non-obese group. In the follow up, there was no differences in sleep profile between groups. This study indicates obesity does not affect the sleep independently of respiratory disorders. Before therapy it is associated with more severe sleep apnea and indirectly with worse sleep quality.