Night owls are at a higher risk of developing heart disease and type 2 diabetes than early birds, new research has found.
Published in Experimental Physiology, the US study found night owls – people who prefer to be active later in the day – have a reduced ability to use and burn fats for energy which allows them to build up in the body.
This can lead to an increased risk of getting type 2 diabetes and heart disease, researchers from Rutgers University in New Jersey found.
On the flip side, early birds – those who are more active in the morning – require more fat as an energy source due to being more energetic with more hours in the day and therefore have higher levels of fitness than night owls.
The researchers put participants into two groups based on their chronotypes – our natural propensity to look for activity and sleep at different times.
After one-week of monitoring, researchers found that early birds use more fat for energy at both rest and during exercise periods than night owls.
Each group was tested at rest before undertaking two 15-minute treadmill workouts – one moderate and one high-intensity.
Following fuel preference monitoring, the individuals were tested for their aerobic fitness levels on an incline challenge with the incline being raised by 2.5% every two minutes until the person got to the point of exhaustion.
‘Early birds are more physically active’
Participants consumed a calorie and nutrition-controlled diet with fasting overnight in order to lower chances of their diets affecting the results.
Senior author and Rutgers University Professor Steven Malin said: “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.”