Owls and larks
Owls are at greater risk of diabetes and heart disease than larks
Sergey Vasiliev, Naked Science
People tend to be active at different times of the day. Scientists distinguish up to six chronotypes, but the most famous are "larks" who wake up early and go to bed early, and "owls" who prefer to get up and fall asleep late.
This difference is not just a matter of habit. It reflects the personal characteristics of biological rhythms and may be associated with differences in brain function and metabolism.
Studies show that the metabolic differences between larks and owls are usually not in favor of the latter. So, recently, scientists from Rutgers University in the USA found out that owls are less sensitive to insulin, dispose of fat stores accumulating in the body worse, and as a result demonstrate a greater risk of developing type II diabetes and cardiovascular diseases. An article about this was published in the journal Experimental Physiology (Malin et al., Early chronotype with metabolic syndrome favors resting and exercise fat oxidation in relation to insulin-stimulated non-oxidative glucose disposal).
For their experiments, Steven Malin and his colleagues selected about 50 volunteers. All of them were a little over 50 years old, led a sedentary lifestyle, but did not suffer from serious illnesses. About half of the participants were larks, half were owls. Metabolic tests were performed at rest and during exercise, showing that larks demonstrate greater sensitivity to insulin.
Recall that insulin is the most important hormone that controls energy and carbohydrate metabolism. High sensitivity of cells to it is considered an indicator of health, and low — up to resistance — is associated with type II diabetes and many other severe disorders. Owls with their reduced sensitivity to insulin use carbohydrates for energy production, while larks rely more on fats and more successfully utilize the reserves that accumulate in the body.
It is worth noting that larks and owls often practice a different lifestyle: larks are more prone to physical activity and an orderly diet. Scientists confirmed this by tracking the daily activity of volunteers and monitoring their food intake. However, the exact relationship between all these factors is not yet clear. It is possible that the increased insulin sensitivity of larks is associated with their generally healthier lifestyle, and not with early activity time.
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