Insomnia is a common complaint for adults with multiple sclerosis and can severely impact health-related quality of life. Point prevalence estimates of insomnia are, however, difficult to determine in this population due to the use of different measurement tools as well as the highly variable clinical presentation of multiple sclerosis. This review consolidates the current evidence base to provide a global estimate of insomnia disorders and symptoms in multiple sclerosis, with consideration of both measurement and sample issues. A comprehensive review of the PUBMED, EMBASE, PsycINFO and CINAHL databases from database inception until January 31st 2023 identified 1649 records, of which 34 (7636 participants total) were eligible for inclusion. Findings were meta-analysed using a random-effects model. Estimates based on self-reported symptoms (52%, CI: 44%-59%) were significantly higher than those obtained by diagnostic tools (22%, CI: 16%-29%). Gender was identified as a potential moderator, with women more likely to report insomnia than men. One in two adults with multiple sclerosis endorse symptoms of poor sleep quality and daytime sleepiness, with 1 in 5 diagnosed with an insomnia disorder. Future research is needed to enhance understanding of these comorbid conditions, including the trajectory of insomnia with disease progression. PROSPERO registration number CRD42021281524.Copyright © 2023 Elsevier Ltd. All rights reserved.