Investigation of the effect of morningness-eveningness on blood pressure in adults

Aim: The biological activities of living organisms occur in a certain rhythm. The biological changes observed in human metabolism due to heat and light during the day are defined as the circadian rhythm.Circadian rhythm regulates physiological events including hunger/satiety, temperature regulation, expression of many genes, endocrine, gastrointestinal, respiratory, immune, cardiovascular and metabolic systems. These physiological and psychological changes due to the rhythms of twenty-four hours; varies according to individual differences. Individual differences in circadian rhythm are expressed by chronotype. Chronotype is categorized as morning, intermediate and evening type. Earlier studies of the evening type; showed that a number of diseases such as bronchial asthma, depression, cardiovascular diseases, spine diseases, obesity, anxiety and negative mood are more common. In the circandian rhythm, there are blood pressure levels that change throughout the day. It is thought that detecting the differences in blood pressure levels according to the circadian types of individuals can predict cardiovascular disease risks. When the literature is examined, it is noteworthy that there is not enough data on this subject. In this study; it was aimed to determine the relationship between chronotypes of adult individuals and blood pressure level. Methods: The study was planned in a cross-sectional, analytical design. It was conducted with a total of 66 individuals, aged between 18-65, who applied to Dokuz Eylul University Education Family Health Centers for any reason, in equal numbers from each chronotype. A questionnaire including the sociodemographic data form and the Morningness-Eveningness Questionnaire was applied to the participants by face-to-face, and 24-hour blood pressure monitoring was done with Holter test. Data were analyzed using SPSS 22.0. Chi-square, t-test, One-way ANOVA were used for statistical analysis and p<0.05 was considered significant. Results: When the chronotype distributions of the participants in our study were examined; all of the 18-24 age group (100%) were found to be evening type, and the majority (55.6%) of the 56-65 age group were found to be morning type (p=0.001). Most of the participants working in shifts (83.3%) were in the evening type, while most of the non-shift workers (36.7%) were in the morning type (p=0.02). It was observed that the majority (50.0%) of those who did not pay attention to a healthy diet were of the evening type (p=0.03). When Holter measurements were examined; 24-hour, daytime, and nighttime mean SBP (systolic blood pressure) were significantly higher in men than women (p=0.02, p=0.02, p=0.05, respectively). When the body mass index is evaluated; obese participants had significantly higher 24-hour and daytime mean SBP, nighttime mean SBP and mean DBP (diastolic blood pressure) (p=0.08; p=0.01; p=0.003; p=0.04, respectively). Those who took care of a healthy diet had significantly lower 24-hour and daytime mean DBP (diastolic blood pressure mean), nighttime mean SBP and mean DBP (p=0.02; p=0.01, p=0.01; p=0.02, respectively). Those who did physical activity for more than 150 minutes a week had significantly higher 24-hour and daytime mean DBP (p=0.01; p=0.007, respectively). Those with dipping blood pressure had significantly lower 24-hour and daytime mean SBP; nighttime mean SBP and mean DBP compared to those with nondipping (respectively; p=0,004, p=0,004, p=0,01, p=0,001).There was no significant difference between the 24 hours, daytime, nighttime mean SBP and mean DBP with the chronotypes of the participants (p>0.05). Conclusion: Hypertension is a chronic and systemic disease and is a common health problem. More work should be done on modifiable parameters such as lifestyle changes that cause hypertension. Studies have shown that chronotype can affect human pathogenesis in different areas. In this study, no difference in arterial blood pressure was found according to chronotypes. Due to the scarcity of studies in the literature dealing with the relationship between blood pressure level and chronotype; we believe that this study will encourage further studies in this field. Key words: Chronotype, Blood pressure, Ambulatory Holter