Objective   To explore the risk factors on non-dipper circadian rhythm of blood pressure in essential hypertension patients.    Methods   A total of 132 diagnosed essential hypertension patients who admitted in the outpatient of our department from March to May 2010 were divided into 49 dippers and 83 non-dippers according to their nocturnal reduction rate of mean arterial pressure (MAP). A cross-sectional survey was carried out on the patients

including the items such as body mass index (BMI)

medical history

target organ damage

salt intake and so on. Their ambulatory blood pressure was moni

tored for consecutive 25 h. Risk factors were screened out by Logistic regression analysis.    Results   Nocturnal systolic BP

diastolic BP

mean arterial pressure

BP load and 24-hour systolic BP

systolic BP load in non-dippers were higher than those in dippers (P0.05). There were more patients older than 60

with target organ damage

being overweight and obese

and having good sleep quality in non-dippers than those in dippers (P0.05). Binary logistic regression analysis showed that increased age (OR=1.071

95%CI 1.027 to 1.117)

target organ damage (OR=5.457

95%CI 2.134 to 13.959)

BMI≥24 kg/m

2

(OR=4.341

95%CI 1.652 to 11.411)

and bad sleep quality (OR=0.948

95%CI 1.039 to 6.403) were major risk factors of abnormal circadian rhythm of blood pressure.    Conclusion   More attention should be paid on drug effect monitoring and life style intervention for the essential hypertension patients getting old

with target organ damage

BMI≥24 kg/m

2

and/or bad sleep quality to prevent and predict non-dipping earlier.