CHRONOTYPE AND MELATONIN PATTERNS IN PATIENTS WITH NOCTURNAL HY-PERTENSION

Objective: Nocturnal blood pressure (BP) is recognised as an important predictor of cardiovascular risk as it has been consistently associated with an increased risk of cardiovascular complications. Circadian rhythms play a role in night-time BP variations and it has been hypothesised that altered chronotype and reduced melatonin secretion could be in part responsible of the deranged diurnal BP profile in patients with nocturnal hypertension. We aimed to comprehensively assess both subjectively and objectively the chronotype of patients with and without nocturnal hypertension.Design and method: Design and Methods: we recruited treated and untreated adult patients with hypertension that under-went ambulatory blood pressure monitoring with a validated device. Patients were then divided ac-cording to the presence of nocturnal hypertension. Chronotypes were estimated both subjectively through Morningness-Eveningness Questionnaire (MEQ) and objectively by collecting saliva samples for melatonin measurement. To compare saliva melatonin secretion pat-terns, we aligned each of the five saliva samples according to the temporal relationship to the first sa-liva sample before dim light melatonin onset (DLMO). Results: Results: 119 patients were included in the study. The main characteristics are summarised as follows: age 59 [54-67] years, 45 (38%) females, BMI was 28.08 (5.13) kg/m2. A total of 61 patients had nocturnal hypertension (SBP 121.5 [112.92-126.44] and DBP 74.52 [71.72-78.67] mmhg) and 58 patients had normal nocturnal BP (SBP 103.15 [99.5-107.6] and DBP 65.12 [61.93-67.63] mmhg, p<0.001). The two subgroups did not differ in age, gender and BMI. No differences were seen with regards to total MEQ score or MEQ derived chronotype although in patients with nocturnal hypertension there was a greater prevalence of MEQ score class intermediate type. (Table 1) In a subgroup of patients with complete melatonin measurement (n=25), although DLMO did not differ there was a tendency towards a lower 1-hour AUC in patients with nocturnal hypertension (28.63 [20.54-32.42] vs 32.56 [30.57-40.48], p=0.07) Conclusions: Conclusions: hypertensive patients with nocturnal hypertension do not exhibit significant differences with regards to chronotype. However, in a subset of patients, lower melatonin production was seen in patients with nocturnal hypertension which deserves further investigation.