Daytime dysfunction is a core element in the diagnosis of insomnia. Excessive daytime sleepiness, fatigue, emotional disturbances and other manifestations are typical symptoms among individuals with insomnia, imposing substantial economic burdens and safety hazards on both patients and society. Thousands of years ago, Huangdi Neijing (The Yellow Emperor's Internal Classic) put forward the theory of "being Energetic in Daytime and Sleeping at Night" (zhou jing ye ming), aligning with modern medicine's recognition of circadian rhythm regulation centered on the sleep-wake cycle. With the rapid development of the economy and society, the prevalence of shift work and rotating work schedules has led to a growing population with circadian rhythm disorders. Modern medicine has consequently attached greater importance to insomnia-induced daytime dysfunction, emphasizing that the diagnosis and treatment of insomnia should focus on patients' daytime functioning and quality of life—a view that aligns well with the "vigorous during the day and tranquil at night" theory in Huangdi Neijing. Currently, a variety of assessment tools are available for the clinical evaluation of daytime dysfunction in insomnia, yet their application lacks systematic standardization. Based on subjective and objective quantitative models, this paper systematically reviews multidimensional assessment instruments for diurnal function in insomnia, and conducts an in-depth analysis and summary of evaluation methods applicable to different populations with insomnia. It aims to explore the target populations and application scenarios of different assessment criteria, which is of great significance for advancing research on daytime dysfunction in the clinical diagnosis and treatment of insomnia.