- Being more active in the morning may be linked to a healthier metabolism, according to new research.
- So-called ‘night owls’ were found to burn less fat and be more resistant to insulin than early bird peers.
- More research could help determine risk of chronic illness based on the body’s natural sleep/wake cycles.
A preference for staying up late may make it harder for your body to burn fat, and could increase your risk of type 2 diabetes and heart disease, new research suggests.
So-called “early birds” who are more active during the day tend to be better able to use fat for energy and are more sensitive to insulin than their “night owl” counterparts, according to a small study published September 19 in the journal Experimental Physiology.
Researchers from Rutgers University and the University of Virginia looked at data from 51 participants, all of whom were sedentary and had metabolic syndrome, a collection of risk factors for chronic illness including high blood pressure and high blood sugar.
Participants were monitored over the course of a week as they underwent a controlled diet and exercise testing.
The participants were divided by chronotype, or their preferred sleep and activity schedule. Early birds in the study were defined as people who tended to be more active in the early hours of the day, while night owls were people who were active later in the evening.
The researchers compared markers of metabolic health, like insulin sensitivity, and ability to burn carbohydrates or fat for energy while resting and during high- and moderate-intensity workouts, between early birds and night owls.
They found the early birds burned more fat for energy, both at rest and during exercise, and were also more sensitive to insulin. In contrast, the night owls used carbohydrates for energy instead of burning fat, and were also more insulin resistant. Both factors could lead to higher risk of illnesses like type 2 diabetes and heart disease for night owls, the researchers wrote.
The results suggest circadian rhythm, the body’s natural sleep/wake cycle, might be used to help assess risk of type 2 diabetes and heart disease, according to Steven Malin, senior author of the study and professor of kinesiology and metabolism at Rutgers University.
“The differences in fat metabolism between ‘early birds’ and ‘night owls’ shows that our body’s circadian rhythm could affect how our bodies use insulin,” Malin said in a press release. “Because chronotype appears to impact our metabolism and hormone action, we suggest that chronotype could be used as a factor to predict an individual’s disease risk.”
Future research could help medical experts identify high-risk people based on their chronotype to provide better preventative care, according to the researchers.
It’s not yet clear why early birds are metabolically different from their more nocturnal peers. One explanation could be that the research required all participants to arrive at the lab early in the morning, which may have been disruptive to night owls’ natural inclination to sleep later, the researchers wrote. Another reason may be that early birds tended to be more aerobically fit overall.
Follow-up studies could help scientists determine the best routine and strategies for overall health, regardless of whether you’re a morning person or like to be up late, according to Malin.
“Further research is needed to examine the link between chronotype, exercise and metabolic adaptation to identify whether exercising earlier in the day has greater health benefits,” he said in the press release.