Excessive daytime sleepiness is a significant health issue, affecting 3.7 to 4.2% of the general population in Western countries. It can be caused by various conditions, including obstructive sleep apnea, narcolepsy, and restless leg syndrome. However, a new syndrome, upper airway resistance syndrome (UARS), has been identified as a cause of excessive daytime sleepiness. UARS is characterized by transient alpha EEG arousals during sleep, which are often overlooked in sleep analyses but have a significant impact on sleep quality. These arousals are linked to increased respiratory efforts during sleep, particularly in the upper airway, and are associated with snoring. The syndrome is diagnosed based on clinical complaints of daytime sleepiness, abnormal multiple sleep latency test (MSLT) scores, and evidence of flow limitation and increased respiratory efforts. Nasal continuous positive airway pressure (CPAP) therapy was found to be effective in treating UARS, significantly reducing transient arousals and improving sleep quality. The study also highlights that UARS is more common in women than in obstructive sleep apnea and hypopnea syndromes. The findings emphasize the importance of recognizing UARS as a distinct condition and using appropriate treatments to address the underlying causes of excessive daytime sleepiness.Excessive daytime sleepiness is a significant health issue, affecting 3.7 to 4.2% of the general population in Western countries. It can be caused by various conditions, including obstructive sleep apnea, narcolepsy, and restless leg syndrome. However, a new syndrome, upper airway resistance syndrome (UARS), has been identified as a cause of excessive daytime sleepiness. UARS is characterized by transient alpha EEG arousals during sleep, which are often overlooked in sleep analyses but have a significant impact on sleep quality. These arousals are linked to increased respiratory efforts during sleep, particularly in the upper airway, and are associated with snoring. The syndrome is diagnosed based on clinical complaints of daytime sleepiness, abnormal multiple sleep latency test (MSLT) scores, and evidence of flow limitation and increased respiratory efforts. Nasal continuous positive airway pressure (CPAP) therapy was found to be effective in treating UARS, significantly reducing transient arousals and improving sleep quality. The study also highlights that UARS is more common in women than in obstructive sleep apnea and hypopnea syndromes. The findings emphasize the importance of recognizing UARS as a distinct condition and using appropriate treatments to address the underlying causes of excessive daytime sleepiness.