['The ankle-brachial index (ABI), ratio of leg blood pressure to arm blood pressure is used extensively as a screening test for stratification of cardiovascular risk. The problems in sleep disturbed nocturnal fall in blood pressure and may relate to development of hypertension. However, the role of sleep quality on ankle-brachial index remains unclear.', 'This study examined 101 patients with essential hypertension. We analyzed the association with ABI on age, sex, body height, body weight, body mass index, waist circumference, blood pressure, HDL-cholesterol, LDL-cholesterol, HbA1c, sleep quality evaluated by Pittsburgh Sleep Quality Index (PSQI), smoking habits, alcohol habits. The ABI is associated with the following seven parameters; body height (r = 0.36, p < 0.001), body weight (r = 0.30, p < 0.005), systolic BP (r = -0.23, p < 0.05), HbA1c (r = -0.24, p < 0.05), PSQI score (rho = -0.31, p < 0.005), alcohol intake (rho = 0.23, p < 0.05) and sex (F = 6.65, p < 0.05). By a multiple linear regression analysis with ABI as the dependent variable after forcing the seven parameters above into the model, body height, HbA1c and PSQI score were significantly associated with ABI (R (2) for the model = 25%, p < 0.001).'] Is lower ankle-brachial index associated with poor sleep quality in patients with essential hypertension?