New research shows that people who stay up late have a decreased ability to burn fat for energy compared to their early rising peers. It also found that night owls may be at higher risk for developing type 2 diabetes compared to early birds.
The research, published in the journal Experimental Physiology, found that wake/sleep cycles have major connections to metabolism. Specifically, a person’s chronotype (whether they’re an early bird or night owl) is linked to how their body burns fats and carbohydrates.
The researchers found that early risers were more adept at burning fat for fuel during exercise and while at rest. Early birds were also more insulin-sensitive, meaning that the cells in their body were better at using blood glucose, keeping down their blood sugar levels.
For the study, 51 participants with metabolic syndrome (conditions such as high blood pressure, high blood sugar, excess fat around the waistline, high cholesterol, and high triglycerides) answered survey questions to determine their chronotype and underwent various procedures to determine their body mass and composition, insulin sensitivity, and how they metabolized carbs and fat. Participants ate controlled diets and were required to fast overnight regardless of when they woke and went to sleep.
Those who reported staying up late were more likely to burn carbs for fuel rather than fat both when fasting at rest and during exercise. Night owls also needed more insulin to break down and use glucose in the bloodstream. These characteristics mean night owls are at higher risk for developing cardiovascular disease and metabolic diseases such as type 2 diabetes.
“The differences in fat metabolism between ‘early birds’ and ‘night owls’ show 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,” study author Steven Malin, Ph.D., explained in a statement.
“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.”
The research team also found that early risers were more physically active and fit, especially early in the day, while those who stayed up late were more sedentary and less fit.
“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,” Malin said.