Our modern day life often seems controlled by the clock, but it is clear that we are also controlling, or changing our own clocks; our circadian clocks, that is. Circadian clocks have developed across all life forms from bacteria to humans, and the evidence of independent evolutionary origins of the different clocks suggests their primary importance. Mammals have complicated clocks that control feeding, metabolism and sleep. Multiple studies in mice have shown weight and insulin sensitivity can be altered by artificially changing day-night cycles, or by changing the time of feeding. These same factors affect us, as we change our circadian clocks, our chronotypes, by staying up later, changing our feeding patterns to later at night, and shortening and disrupting our sleep. A study of chronotypes in people with type 2 diabetes found that those who had shifted their chronotypes to later in the day tended to skip breakfast, eat more calories at supper, have a higher perceived sleep debt and higher weights and A1C values. Our recent post noted the new American Heart Association recommendations on timing of meals, which included shifting calorie intake to earlier in the day.
See today’s excellent review, by a leader in the field