We examined subjective symptoms ( snoring intensity , frequency , witnessed apnea , and daytime sleepiness ) and objective snoring and respiratory parameters ( snoring duration -LSB- proportion of sleep while snoring louder than @ dB -RSB- , snoring loudness , apnea-hypopnea index , respiratory disturbance index , minimum arterial oxygen saturation , and oxygen desaturation index@ % ) at @ to @ months after surgery .