Related Experiment Video
Updated: May 23, 2025

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Toward a personalized chronotherapy of blood pressure
Germaine Cornelissen1, Yoshihiko Watanabe2, Larry A Beaty1
1Halberg Chronobiology Center, University of Minnesota, Minneapolis, MN, USA.
Background:
A consensus regarding the optimal time to administer anti-hypertensive medications has not been reached. Possible differential effects of different anti-hypertensive drugs on the circadian pattern of blood pressure (BP) and differential responses of individual patients receiving the same treatment at different times of the day may partly account for the controversy.
Methods:
Ambulatory blood pressure monitoring (ABPM) data available at 30-min intervals for 7 days from previous studies are reanalyzed to compare the effect of five drugs (amlodipine, atenolol, captopril retard, long-acting carteolol, and nilvadipine) taken 1.5 h after awakening or twice a day on the 24-h profile of BP from 7 to 13 conventionally diagnosed patients per treatment group. Similar data from 30 patients receiving losartan/hydrochlorothiazide for at least one month at each of six different times in relation to their time of awakening serve to compare the effect of treatment time in different patients.
Results:
Some but not all drugs affected the 24-h amplitude and/or phase of BP or the contribution of the 12-h harmonic term to modify the circadian waveform of BP. While evening dosing increased the 24-h amplitude of BP in some patients, other patients achieved such a desired effect with morning dosing.
Conclusion:
Personalized optimization of treatment timing to best match a healthy circadian BP pattern is recommended, guided by chronobiological analyses of ABPM data collected over several days in view of the large day-to-day variability in all features of the 24-h BP rhythm.
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Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
Measurement of Blood Pressure
Assessment of blood pressure in brachial artery(one-step method)
Prepare for the Procedure:
Equipments Used To Measure Blood Pressure
This invasive approach involves cannulating a peripheral artery. During each cardiac contraction, pressure generates mechanical motion within the catheter, transmitted through rigid, fluid-filled tubing to a transducer. This transducer converts mechanical motion into electrical signals displayed as waveforms on a monitor. An automatic flushing system prevents blood backflow. Due to the potential risk of unexpected arterial blood loss, this method is primarily used in intensive...

