Night owls more likely to develop diabetes, heart disease than early birds

LONDON — Staying up late can be fun, but a new study finds it can also be bad for your heart and overall health. Researchers have found that “night owls” are more likely to develop type 2 diabetes or heart disease than people who get to bed and wake up early.

Not only did they discover that night owls are less active than early birds, they found they are less sensitive to insulin — which both act as predictors for type 2 diabetes and cardiovascular disease.

The study also reveals that those who stay up later are worse at using fat for energy and this fat can build up in the body — contributing to disease risk. Meanwhile, “early birds” appear to be more reliant on fat for energy, more active in the day, and more aerobically fit.

Researchers at Rutgers University split participants into two groups, early and late, based on their “chronotype.” This is a human’s natural propensity to seek activity and sleep at different times.

The team used advance imaging, assessed body mass, body composition, insulin sensitivity, and fat and carbohydrate metabolism using breath samples to each participant’s sleep trends. Over a week, the team monitored participants to figure out their daily activity patterns.

To minimize diets impacting the results, study authors also required the groups to follow calorie and nutrition-controlled diets and fast overnight.

‘The insulin hormone has major implications for our health’

Researchers tested each group at rest before completing two 15-minute sessions of exercise on a treadmill, one moderate and one high intensity. Inclines on the running machine increased by 2.5 percent every two minutes until each participant reached exhaustion.

Scientists discovered early birds use more fat for energy, both when resting and during exercise. They were also more insulin sensitive.

Meanwhile, night owls were insulin resistant, and their bodies required more insulin to decrease blood glucose levels. Night owls’ bodies also preferred carbohydrates as their energy source, rather than fats.

Writing in the journal Experimental Physiology, the team says night owls’ impaired ability to respond to insulin and use more fuel can indicates a higher risk of type 2 diabetes and heart disease.

“The differences in fat metabolism between ‘early birds’ and ‘night owls’ shows that our body’s circadian rhythm (wake/sleep cycle) could affect how our bodies use insulin. A sensitive or impaired ability to respond to the insulin hormone has major implications for our health,” says senior author Professor Steven Malin of Rutgers University in a media release.

“This observation advances our understanding of how our body’s circadian rhythms impact our health. 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.”

“We also found that early birds are more physically active and have higher fitness levels than night owls who are more sedentary throughout the day. 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,” Prof. Malin concludes.

SWNS writer Pol Allingham contributed to this report.