Background <p>Sleep disturbances are plausible and potentially modifiable clinical and behavioural markers of risk for assisted reproduction outcomes, but their causal role and the most appropriate targets of intervention remain uncertain, and findings across cohorts are mixed.</p> Methods <p>We registered a protocol in PROSPERO under CRD420251118366 and followed PRISMA guidance. We searched PubMed, Embase, Web of Science, and the Cochrane Library through August 3, 2025. Eligible studies included adult women undergoing in vitro fertilization or intracytoplasmic sperm injection, measured sleep disturbances including obstructive sleep apnea, subjective sleep quality, or sleep duration, and reported adjusted associations with oocyte yield, fertilization, embryo quality, implantation, clinical pregnancy, or live birth. We pooled adjusted odds ratios using random effects and also presented fixed effects for comparison. Heterogeneity was assessed with Q and I². We conducted leave one out analyses and used influence diagnostics.</p> Results <p>Fourteen prospective IVF/ICSI cohorts involving 9,902 women met the inclusion criteria, and seven contributed data to meta-analyses. Sleep-disordered breathing, predominantly obstructive sleep apnea, was consistently associated with lower treatment success: pooled odds ratios were 0.52 (95% confidence interval [CI] 0.36–0.75) for clinical pregnancy and 0.47 (95% CI 0.30–0.73) for live birth, with no between-study heterogeneity. Poor subjective sleep quality, defined by a Pittsburgh Sleep Quality Index (PSQI) global score &gt; 5, was associated with lower clinical pregnancy under fixed-effects models (pooled odds ratio 0.78, 95% CI 0.67–0.91), whereas the corresponding random-effects estimate was imprecise and compatible with no association. Limited data on sleep duration and timing suggested a possible U-shaped pattern, with both short and long sleep linked to adverse intermediate outcomes, but heterogeneity in exposure definitions, assessment windows, and reported endpoints precluded a single quantitative synthesis.</p> Conclusions <p>Objectively confirmed sleep-disordered breathing is associated with lower odds of clinical pregnancy and live birth after assisted reproduction. Associations for perceived sleep quality are model-dependent and attenuate when between-study heterogeneity is considered. Given the limited and observational nature of the available evidence, these results do not support routine targeted sleep screening as a standard component of infertility evaluation, but they indicate that sleep-disordered breathing may be relevant to consider when clinically indicated. Randomized trials are needed to determine whether treating sleep-disordered breathing improves reproductive endpoints and to clarify the contribution of upstream metabolic, psychological, and circadian factors.</p>