Is chronotype a risk factor for nocturnal non-dipping hypertension in children?

Objectives: Chronotype is an individual circadian rhythm pattern affecting vascular tone and blood pressure. We aimed to investigate the effect of chronotype on nocturnal dipping in children with essential hypertension. This study was conducted considering that the habit of sleeping late at night has become widespread in children, especially during adolescence, potentially leading to the non-dipping phenomenon. With this study, we wanted to draw attention to the importance of sleep patterns and quality. Material and Methods: This is a cross-sectional study, which was performed at Adiyaman University Faculty of Medicine between July 15, 2022, and March 15, 2023. All patients received 24-hour ambulatory blood pressure (BP) monitoring with essential hypertension based on the American Academy of Pediatrics guidelines. A chronotype questionnaire was administered to collect data from the participants. Results: A total of 49 patients were included in the study, comprising 14 (29%) girls and 35 (71%) boys. The mean age of the patients was 13.9±2.3 years. Based on the chronotype questionnaire, 2 (4%) patients were identified as morning type, 23 (47%) as evening type, and 24 (49%) as intermediate type. Chronotype was not significantly associated with hypertension stage (p = 0.88) or the dipping phenomenon. In the intermediate type group, nighttime systolic BP dipping was 9.9±6% and in the evening type group, nighttime systolic BP dipping was 9.8±4.9% (p = 0.88). In the intermediate type group, nighttime diastolic BP dipping was 12.7±7.3% whereas in the evening type group it was 14.4 ± 6.4% (p = 0.58). Chronotype was not significantly associated with hypertension type [(p = 0.95) for systolic hypertension, (p = 0.58) for diastolic hypertension]. Conclusion: Chronotype affects nocturnal dipping in essential hypertensive children. In our study, the very low number of the morning type suggests that there are problems with sleep patterns and quality, especially late falling asleep, among adolescents. Sleep health, quality, and average daily sleep duration, and how they affect blood pressure levels in children, are a public health problem.