INTRODUCTION Intensive sleep related sweating (ISRS) is a common complaint among sleep apnea patients; often disappearing with successful continuous positive airway pressure (CPAP) treatment. However few studies have focused on ISRS as a symptom of obstructive sleep apnea (OSA). We report preliminary data from an ongoing study on ISRS before and after CPAP treatment.

METHODS Patients underwent full polysomnography including measurements of skin temperature, core body temperature and electrodermal activity (EDA). Data evaluation was done in a standard manner, i.e., sleep scoring and AHI (apnea-hypopnea index) calculation. EDA index (events/hour sleep) was assessed, considering an EDA event a change in skin potential of >50 mV amplitude and >1,5 sec duration.

RESULTS Altogether, five otherwise healthy male OSA patients have been studied before and after 3 months on CPAP treatment. The five patients (mean age 50, range 25-61) had a mean AHI = 46 (range 33-64) before treatment and mean AHI = 4 (range 0.5-10) after treatment. The mean EDA index was significantly higher (p = 0,05) before treatment (mean 129, range 18-301) than after (mean 42, range 3-131). A significant difference was found in EDA index between sleep stages S1 + S2 versus S3 + S4 versus REM within subjects for each sleep recording (p = 0,003) with the highest index in S3 and S4. EDA events were not correlated in time to the occurrence of apneas.

DISCUSSION Sweating occurs mostly during S3 and S4 in both untreated and treated OSA patients, but is reduced with treatment. More research is needed to explain the causal relationship between sweating and OSA.