Introduction: In hypertensive individuals, lack of adequate reduction in night-time BP is associated with higher cardiovascular risk. Although the underlying causative mechanisms responsible for lack of nocturnal decline in BP have still yet to be completely elucidated, previous studies established that non-dippers are older, obese, and have poorer sleep quality, and autonomic dysfunction. In this study we aimed to investigate whether some potential behavioural and life style factors may also contribute to the lack of nocturnal decline in hypertensive patients.
Methods: In this cross-sectional study, newly diagnosed or treated hypertensive patients (18–65years old) with a 24 hour ABPM record were asked to fill-in a special questionnaire about their life style characteristics and behavioural factors. Subjects with any known cardiovascular disease, diabetes mellitus, psychological disorder, chronic systemic illness, and OSAS were excluded from the study. Subjects' sleep quality were assessed via the Pittsburgh Sleep Quality Index. Certain eating habits of subjects were evaluated through a special questionnaire assessing 4 main items: 1-Med-diet score, 2- Regular breakfast eating (>5 times in a week), 3-Late night eating (last meal or snack to sleep <2 hours) and 4-Salt restriction (Strict-moderate-no/mild based on self report). Physical activity level of the subjects were assessed via short form of International Physical Activity Questionnaire; and subjects were classified as sedentary (<600 MET-min/week) or active (>600 MET-min/week). Smoking status, active working status, hypertension duration, BMI and routine biochemical tests of the patients were recorded. Patients with non-satisfying questionnaire forms, mean systolic BP >165mmHg and/or diastolic BP >110mmHg, and Cre >1.5 were excluded from the study.
Results: 721 hypertensive subjects were suitable for final analysis. There were 376 non-dipper hypertensives and 345 dipper hypertensives. Comparison of these two groups showed that, non -dipper hypertensives were older (54.6±17.2 vs 51.1±16.7 years, p=0.020), had a longer duration of hypertension (median: 5 years vs 4 years, p=0.031), had higher BMI values (25.5±5.6 vs 23.3±6.7, p=0.019) and a higher percentage of late night eating pattern compared to dippers (24.2% vs 14.2%, p=0.028). Other parameters involved in the analysis were not significantly different between these two groups. In multivariate analysis duration of hypertension (OR: 1.035, 95% CI: 1.002–1.065, p=0.041) and late night eating (OR: 2.81, 95% CI: 1.079 -8.351, p=0.036) were identified as the parameters independently associated with non-dipper hypertension.
Conclusion: This study showed that late night eating may be an important contributing factor in development of non-dipper hypertension. We think that, healthy eating patterns in terms of ideal frequency and timing of the meals should be identified to improve cardiovascular health of the population.