<p>Traumatic brain injury (TBI) is a major global public health problem, with a high burden of long-term sequelae that extend beyond acute survival and physical recovery. Sleep disturbances are increasingly recognised as a common and clinically significant consequence of TBI, yet they remain under-recognised and inadequately addressed, particularly in low- and middle-income countries such as Vietnam. This study aimed to assess sleep quality and to identify factors associated with sleep disturbances among patients with TBI in Vietnam. A cross-sectional study was conducted in 2020 through phone interviews among 212 TBI patients in Vietnam. Data on demographics and socioeconomic status, health risk behavior, mental health issues, social support, and sleep quality were collected. Multivariate Tobit regression and Multivariate Logistic Regression models were used to determine factors related to the PSQI score and sleep disturbances among TBI patients. A total of 212 adults with TBI were enrolled (mean age 47.1 ± 17.6 years, and 67.5% were male), nearly half of the participants (47.2%) reported sleep disturbances. The majority experienced mild TBI (93.9%), and road traffic accidents were the leading cause of injury (65.6%). Individuals with sleep disturbances indicated a significantly higher prevalence of depressive symptoms compared with those without sleep disturbances (38.0% vs. 7.1%, <i>p</i> &lt; 0.001). In addition, perceived social support was significantly lower among participants with sleep disturbances than normal sleep quality (<i>p</i> &lt; 0.001). Multivariable regression analysis indicated that being female, hazardous drinking, and higher depressive symptom scores were associated with poorer sleep quality, whereas higher educational levels and stronger perceived social support were associated with better sleep outcomes. This is one of the first studies in Vietnam to examine sleep disturbances and their associated factors among patients with TBI. The findings indicate a high prevalence of sleep disturbances and highlight significant associations between sleep quality and sociodemographic characteristics, depressive symptoms, perceived social support, and health behaviors. This study underscores the importance of recognizing sleep disturbance as a key outcome in TBI care and highlights the need for integrated, multidisciplinary rehabilitation interventions that address sleep, mental health, and social functioning, with particular attention to vulnerable groups such as women, individuals with lower educational attainment, and those with substance use.</p>