The objectives of this study is to compare short-term outcomes of CPAP and TRD in the treatment of obstructive sleep apnea. Study design is a randomized cross-over trial during 3-weeks period of each treatment in 36 patients. Primary outcomes are quality of life, degree of sleepiness, and severity of OSA determined by FOSQ ESS, and AHI or RDI, respectively. Wash-in period 1 week and Wash-out periods 1 week are required before start each treatment.