They found that early risers rely more on fat as an energy source and their activity spans a larger arc of diurnal hours, meaning fat may build up more easily in late-nighters, the scientists found. 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 becomes relevant as it explains why night owls are at greater risk of Type 2 diabetes and cardiovascular disease and can help doctors circle off a group which is at potential risk.“This could help medical professionals consider another behavioural factor contributing to disease risk,” Prof Steven Malin, a senior author on the study and expert in metabolism at Rutgers University, was quoted as saying.“There are a lot of studies on diet, weight loss, sleep pattern, but heart diseases are multi-factorial. We cannot say doing any one thing will be beneficial for our patients. Having said that, if we look at the conclusions logically, then a person who stays up late at night is likely to snack more and if a person wakes up early, is much more likely to go for a walk or do yoga in the morning. All the factors such as diet, exercise, obesity, diabetes, hypertension, family history and other reasons together impact heart health,” said Dr VK Bahl, Principal Director of Cardiac Sciences at Max Healthcare and former head of the Department of Cardiology at the All India Institute of Medical Sciences.The researchers divided 51 obese middle-aged adults into two groups, depending on their answers to a questionnaire on sleeping and activity habits. They monitored the volunteers’ activity patterns for a week and tested their bodies’ energy threshold at rest and while performing moderate or high-intensity exercise on a treadmill. Early birds were found to be more sensitive to insulin and burned more fat than night owls while at rest and during exercise. The night owls were less sensitive to insulin and their bodies favoured carbohydrates over fat as an energy source. “Night owls are reported to have a higher risk of obesity, Type 2 diabetes and cardiovascular disease when compared with early birds. A potential explanation is they become misaligned with their circadian rhythm for various reasons. If a person is a night owl, they may prefer to go to bed late but still have to get up early to go to work or to look after children, and this may force them to be out of alignment with their body clocks when they would rather be sleeping,” Prof Malin was quoted as saying.
“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,” Prof Malin said 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. 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 added.