Background. Sleep is a basic physiological process. Normal sleep yields decrease in sympathetic activity, blood pressure ( BP) and heart rate. Those, who do not have expected decrease in their BP are considered "non-dippers''. We aimed to determine if there was any association between the non-dipping status and sleep quality, designed a cross-sectional study, and enrolled and evaluated the sleep quality of relatively young patients with an initial diagnosis of hypertension. Methods. Seventy-five consecutive patients, diagnosed to have stage 1 hypertension by their primary physicians, were referred to our study. Patients had newly diagnosed with stage 1 hypertension. Patients with a prior use of any anti-hypertensive medication were not included. Eligible patients underwent the Pittsburgh Sleep Quality Index (PSQI), which has an established role in evaluating sleep disturbances. All patients underwent ambulatory BP monitoring. Results. There were 42 non-dipper patients (mean age = 47.5 +/- 11.9 years, 24 male/18 female), as a definition, 31 dipper hypertensive patients (mean age = 48.5 +/- 12.8 years, 21 male/10 female) and two with white coat hypertension. Daytime systolic and diastolic mean BPs were not significantly different between the two groups. Night-time mean systolic and diastolic BPs were significantly higher in non-dippers compared with dippers. PSQI scores, globally, were significantly higher in non-dippers compared with dippers. Total PSQI score was not correlated with body mass index. It was noticed that, individually, sleep quality, sleep efficiency and sleep disturbance scores were significantly higher in non-dippers. Being a poor sleeper in terms of high PSQI score (total score > 5) was associated with 2.955-fold increased risk of being a non-dipper (95% confidence interval 1.127-7.747). Conclusion. We showed that the risk of having non-dipping hypertension, a risk factor for poor cardiovascular outcomes among hypertensive individuals, was tripled (odds ratios) among poor sleepers. We think that evaluating sleeping status and sleep quality among the hypertensive population may help unmask non-dipper hypertension, enabling physicians to treat appropriately.