Endogenous blood pressure circadian rhythm in normotensive young adults: how it looks and how it differs from the results of ambulatory blood pressure monitoring

Aim. Comparative study of the endogenous circadian rhythm of blood pressure (BP) depending on the parameters of ambient light and in comparison with the results of Ambulatory Blood Pressure Monitoring (ABPM). Material and methods The endogenous component of BP circadian rhythm was studied using our modification (Gubin et al., 2017) of standard «constant routine» protocol (CR). BP measurements were taken every 2 hours during the 24-hour period in two regimen of ambient light: LD (light-dark, light intensity > 400 lx from 09:00 to 17:00. and 400 lx during the whole study). The data are compared with the results of the 7-day ABPM of healthy young adults in a regular life with activity period from 07:00 to 23:00 h and sleep from 23:00 to 07:00 h (Control group). Results Endogenous circadian rhythm of BP is still bimodal with a predominance of the evening peak. Prominence of the morning peak, presumably, decreases with a decreasing ambient light signaling, i. e. light intensity. Diurnal physical activity significantly increases only SBP, but not DBP. Night sleep, on the contrary, significantly lowers only DBP, but not the SBP. Conclusions Our study confirms predominance of the evening peak of the endogenous circadian rhythm of BP. The level of motor activity and sleep have a significant impact on the circadian rhythm of BP, however, SBP and DBP in different degree depend on diurnal activity vs. nocturnal sleep in healthy young adults. The nature of the evening endogenous BP circadian rhythm acrophase remains poorly understood and requires purposeful further research to clarify underlying mechanisms.