This systematic review and meta-analysis aim to investigate the prevalence rates of various types of sleep disturbances among head and neck cancer (HNC) patients before, during, and after cancer treatment. We performed a systematic search on PubMed, Embase, CINAHL, and PsycINFO to find studies that reported the prevalence of any type of sleep disturbance among adult HNC patients. Meta-analyses of prevalence were performed using random effects models, with I2 values to indicate the extent of heterogeneity. In total, 29 studies of accumulatively 2315 HNC patients were included. The quality of the studies was fairly low and the heterogeneity was high. Studies on three types of sleep disturbances were found: insomnia (17 studies), hypersomnolence (12 studies), and sleep-related breathing disturbances (14 studies). The prevalence of insomnia was 29% (95% CI 20–41%) before treatment, 45% (95% CI 33–58%) during treatment, and 40% (95% CI 24–58%) after treatment, while for hypersomnolence the prevalence was 16% (95% CI 7–32%) before treatment and 32% (95% CI 20–48%) after treatment. The prevalence of sleep-related breathing disturbances before and after treatment was 66% (95% CI 44–82%) and 51% (95% CI 34–67%), respectively. These results imply that sleep disturbances are highly prevalent among HNC patients before, during, and after treatment.