Excessive daytime sleepiness (EDS) is a clinical condition characterized by an inability to maintain alertness and wakefulness during the daytime, leading to diminished vigilance, impaired daytime functioning, and increased risks of traffic or occupational accidents. The core pathophysiology involves disrupted sleep architecture and dysfunction of brain arousalpromoting systems, which can stem from diverse etiologies including sleep disorders, systemic diseases, psychiatric disorders, and medication/substance use. Clinically, high-risk populations for EDS include occupational drivers and transportation workers, shift workers, individuals with chronic systemic diseases or psychiatric disorders, and users of sedative substances. Diagnosis of EDS relies on a detailed medical history and sleep/wake cycle assessment, supplemented by subjec‐tive scales (e.g., Epworth sleepiness scale) and ob‐jective tests such as polysomnography (PSG) and the multiple sleep latency test (MSLT). It is crucial to differentiate EDS from fatigue. Currently, there is no universally standardized treatment protocol for EDS. Management focuses on addressing underlying causes and alleviating symptoms, often combined with wake-promoting agents (WPAs) for sufficient therapeutic effect. This article summarizes the etiology, pathophysiological mechanisms, high-risk populations, diagnostic approaches, and current treatment strategies for EDS. It also proposes future research directions to advance standardized clinical management and promote precision medicine in EDS diagnosis and therapy.