<p>Sleep disturbance is increasingly recognized as an important dimension of morbidity in chronic spontaneous urticaria (CSU), yet existing evidence remains fragmented across clinical, psychosocial, and physiologic domains. We conducted a systematic review of studies identified through PubMed, Embase, Web of Science, CENTRAL, and ClinicalTrials.gov to evaluate the prevalence, associated factors, and biologic correlates of sleep dysfunction in CSU, including subjective and objective sleep measures, sleep-disordered breathing (SDB), and potential biomarkers. Across cohorts, sleep disturbance was consistently reported and was more common in patients with CSU than in controls. Patients with CSU generally demonstrated worse global sleep quality, shorter sleep duration, longer sleep latency, and greater insomnia severity. Poor sleep was commonly associated with higher disease activity (UAS7), lower disease control (UCT), and worse quality of life (QoL) outcomes. Sleep impairment frequently co-occurred with anxiety, depression, fatigue, headache, and additional systemic symptom burden. Emerging biomarker data suggested possible circadian-immune dysregulation, including altered melatonin and orexin signaling in patients with CSU. SDB, including increased obstructive sleep apnea (OSA) risk and higher apnea–hypopnea indices, was reported in select cohorts and was generally more frequent among patients with greater urticaria activity. Limitations include heterogeneity in study design and the predominance of cross-sectional data, with limited objective sleep testing and biomarker assessment across cohorts. Despite these considerations, the available evidence indicates that sleep dysfunction in CSU is common, multifactorial, and clinically meaningful, supporting routine sleep assessment to improve comprehensive disease management.</p>