The rate at which our body expends energy at rest was for the first time accurately associated with circadian rhythms.
The human body "burns" calories not only during active exercise, but also at rest. Energy is required constantly - both for breathing and for the work of internal organs, including the brain, and to maintain the desired body temperature. Until now, scientists could not say for sure how stable this flow rate is or changes depending on changes in the daily activity of the body, which is set by circadian rhythms.
However, new work by the team of Harvard School of Medicine professor Jeanne Duffy has shown that our bodies use more energy in the afternoons, even at rest, than in the morning. The researchers write about this in an article published in the journal Current Biology.
The authors worked with seven healthy volunteers who were isolated for three weeks in a windowless room with fully artificial lighting. This made it possible to clearly regulate the rhythms of their "internal biological clock": every next day, "night" for them came four hours later than the previous one.
The daily frequency of energy expenditure at rest was found in all experimental subjects, although the exact moment of the onset of the maxima and minima could differ quite noticeably. On average, the peak fell on about 17 hours of an artificially regulated day, although in some people it could occur at both 14 and 20 hours. This burned about 129 calories more than the average. And the minimum - about five hours of artificial morning - ranged from two to eight hours.
According to scientists, such variability is completely normal for the circadian rhythms of different people, it's not for nothing that some of us are considered "owls", and others - "larks." Nevertheless, the general scheme remains unchanged for both those and others: the regularity of the daily rhythms of activity is reflected in energy expenditure.
Sergey Vasiliev