This study was performed to determine the frequency and degree of sleep disturbance in patients with dizziness using the Pittsburgh Sleep Quality Index, Japanese Version (PSQI-J), and investigate the relationship between dizziness and sleep disturbance. Fifty-two patients (20 male, 32 female) with a chief complaint of dizziness visited the dizziness clinic of the Department of Otolaryngology, Tokyo Medical University, for 3 months in 2013. The patients' age (average ± standard deviation) was 54.4±17.0 years (range, 10-88 years). The average PSQI global score was 7.6±4.2 points, which exceeds the 5.5-point cut-off for insomnia. In total, 67.3% of patients scored >6 points, and 35.8% scored >9 points, indicating definite sleep disturbance. With respect to the demography of disease groups, patients with Meniere's disease scored an average of 7.9 points, those with autonomic imbalance scored 8.8 points, and those with psychogenic dizziness scored 9.7 points; all of these diseases were associated with high PSQI scores. Patients with benign paroxysmal positional vertigo and patients with no abnormal findings showed relatively low scores (6.7 and 5.3 points, respectively). Patients with suspected sleep apnea syndrome, restless leg syndrome, and parasomnias tended to show high scores (>10 points). A high rate and high grade of sleep disturbance were confirmed in patients with dizziness, indicating that sleep quality affects several types of dizziness and vertigo. Understanding sleep disorders is helpful for the diagnosis and treatment of dizziness and provides a new perspective on the etiology of dizziness.
