Objective: Standard overnight polysomnography (PSG) scores only the apneahypopnea index (AHI) as a predictor of sleep apnea. It is proven that the arousals also contribute especially to the daytime symptoms of obstructive sleep apnea syndrome (OSA). The authors aimed to search the relevance of arousals and obstruction site in the upper airway with the sleep parameters, daytime sleepiness and the sleep quality. Materials and Methods: A total number of 118 subjects were recruited. All of them received a full-night attended PSG and a thorough otolaryngologic examination to identify the site of obstruction in the upper airway and 2 different sleep questionnaires to present the daytime sleepiness and the sleep quality. Results: The level of nasal airway blockage had no impact on AHI, daytime sleepiness and the sleep quality. The increase in level of tonsillar hypertrophy had a negative impact on oxygen desaturation index (ODI) only (P = 0.021). The level of retrolingual obstruction worsen ODI (P = 0.022), AHI (P = 0.041), daytime sleepiness (P = 0.047) and sleep quality (P = 0.033). Conclusion: Arousals during sleep deserve better attention in scoring PSG events, as they reliably reflect daytime somnolence and sleep quality. Retrolingual obstruction was the main contributor for cortical arousals. It is imperative to cure retrolingual obstruction properly which may be easily detected in sleep endoscopy.