People who are ‘night owls’ may have a higher risk of type 2 diabetes and heart disease than those who are ‘early birds’
What is the main question of this research?
Chronotype reflects differences in hormonal and metabolic profiles mediated by the circadian rhythm. But does resting and/or exercise fuel use differ in the early versus late chronotype as it relates to insulin sensitivity?
What are the main findings and their significance?
The early chronotypes with metabolic syndrome used more fat during rest and exercise, regardless of aerobic fitness, compared to late chronotypes. Early chronotypes were also physically more active during the day. Greater use of fat is associated with the elimination of non-oxidizing glucose. These findings suggest that early chronotypes have differences in fuel selection that are associated with type 2 diabetes risk.
Early chronotype with metabolic syndrome favors fat oxidation at rest and exercise compared with insulin-stimulated non-oxidative glucose disposal
The chronotype it is a circadian classification that identifies an individual’s preference for performing an activity or recognizing alertness at different times of the day. The early chronotypes (CD), i.e. preferences for getting up early and/or being active earlier in the day tend to have a reduced risk of cardiovascular disease (CVD), including low triglycerides and C-reactive protein, with high-density lipoprotein (HDL). Additionally, ECs tended to engage in more general physical activity (GA) than their late chronotype (LC) counterparts.
The exact biological mechanisms by which chronotype confers increased disease risk are unknown, but insulin sensitivity it is an important etiological factor in the progression to type 2 diabetes and CVD. Additionally, the inability to switch between lipid and carbohydrate fuel sources from a fasted to a fed state, known as metabolic inflexibilitymay precede insulin resistance.
The carbohydrates they are considered the primary source of energy during moderate-to-high-intensity exercise in healthy controls, although exercise is known to reduce dependence on glycogen/glucose flux and increase fat oxidation. Somewhat inconsistent with the fasting fat oxidation observations is that individuals with insulin resistance, prediabetes, and/or type 2 diabetes have lower muscle glycogen utilization and higher fat oxidation during exercise than their healthy counterparts.
This is said to be due to several factors an apparent paradox (eg, excess lipids and/or impaired oxidative capacity), but no study to date has examined the influence of chronotype on exercise fuel selection. This is biologically relevant because the circadian rhythm is a major feature of chronic disease risk, in part through changes in energy metabolism. In fact, we recently reported that people classified as CD are more sensitive to insulin in relation to insulin-stimulated carbohydrate utilization, a marker of metabolic flexibility.
Our business models and cycles of sleep/wake may affect the risk of diseases such as type 2 diabetes and heart disease. New research published in Experimental Physiology found that the cycles of sleep/wake they cause metabolic differences and change our body’s preferences for energy sources. Researchers found that those who stayed up later had a reduced ability to use fat for energy, meaning that fat can accumulate in the body and increase the risk of type 2 diabetes and cardiovascular disease.
Metabolic differences relate to how well each group can use insulin to promote the uptake of glucose by cells for energy storage and use. the people who are “early risers” (people who prefer to be active in the morning) rely more on fat for energy and are more active during the day with higher levels of aerobic fitness than “night owls”. On the other hand, “night owls” (people who prefer to be active later in the day and at night) use less fat for energy at rest and during exercise.