Not all patients with the Obstructive Sleep Apnea Syndrome (OSAS), mostly mild, have excessive daytime sleepiness. Sleep fragmentation provides the performance decrease with increasing reaction time to external stimuli and correlates with excessive sleepiness. So, the study aims at assessing the effect of sleep fragmentation on the Reaction Time and it`s maintenance in patients with OSAS compared with healthy, to better clarify were patients with and without somnolence differ. For that, will be recruited 30 male volunteers aged between 20 and 50 year old to participate in the study. They will be distributed in three groups: "CONTROL" (without symptoms of sleepiness and apnea and hypopnea index (AHI) less than 5), "SS" (with AHI between 5 and 15 without symptoms of somnolence) and group "CS" (with AHI between 5 and 15 with symptoms of somnolence). The groups will undergo a polysomnography and subsequently, the Test and Maintenance of Wakefulness and PVT Battery Tests. The reaction time will be compared, as well as the ability to keep the reaction time over time between groups to see whether there is a difference between the motor performance throughout the day and the perception of sleepiness.