Background Depression and anxiety are common mental health problems that are strongly associated with sleep disturbances, according to community-based researches. However, this association has not been investigated among patients admitted for cardiovascular diseases (CVDs). We examined the prevalence of depression and anxiety in inpatients with various CVDs and their association with sleep disturbances. Materials and methods This cross-sectional study included 1294 patients hospitalized for CVDs in a Japanese university hospital were evaluated for their mental status using the Hospital Anxiety and Depression Scale (HADS), for sleep-disordered breathing (SDB) using pulse oximetry, and for sleep quality using the Pittsburgh Sleep Quality Index (PSQI). Results Patient characteristics were as below: mean age, 63.9±14.7 years; 25.7% female. Overall, 18.9% had depression (HADS-depression[greater than or equal to]8) and 17.1% had anxiety (HADS-anxiety[greater than or equal to]8). The presence of depression was associated with female sex, older age, higher plasma brain natriuretic peptide level, lower estimated glomerular filtration rate, and the prevalence of heart failure. Overall, 46.5% patients were categorized as having a poor sleep quality (PSQI 5), and 28.5% patients had SDB (3% oxygen desaturation index 15). Although depression and anxiety were not associated with SDB, they were independently associated with poor sleep quality (OR = 3.09, 95% CI 2.19-4.36; OR = 3.93, 95% CI 2.71-5.69, respectively). Conclusions Depression and anxiety were not uncommon in patients with CVDs. Poor sleep quality could be an important risk factor linked to psychological disturbances.