Do you like to get up in the morning or do you prefer the nightlife? Our activity and sleep can influence our risk of diseases such as type 2 diabetes and heart disease. New research published in Experimental Physiology found that wakefulness / sleep cycles cause metabolic differences and alter our body’s energy preferences. Scientists have found that people who are awake have a reduced ability to use fat as energy, which means that fats can accumulate in the body and increase the risk of type 2 diabetes and cardiovascular disease.
The metabolic differences are about how well each group can use insulin to promote cellular uptake of glucose for energy storage and use. People who are „early birds” (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 capacity than „night owls”. On the other hand, night owls (people who prefer to be active later in the day and night) use less fat for energy at rest and during exercise.
Researchers at Rutgers University, New Jersey, USA divided participants (n = 51) into two groups (early and late) based on their „chronotype” – our natural tendency to seek activity and sleep at different times. They used advanced imaging to assess body weight and composition, as well as insulin sensitivity and breath samples to measure fat and carbohydrate metabolism.
Participants were monitored for one week to assess their activity patterns throughout the day. They ate a calorie-controlled diet and nutrition, and had to fast overnight to minimize the impact of the diet on performance. To investigate fuel preferences, they were tested at rest before completing two 15-minute series of exercise: one moderate session and one high-intensity treadmill session. Aerobic fitness levels were tested through an incline challenge where the incline was increased by 2.5% every two minutes until the participant reached the exhaustion point.
