Night owls at greater risk of type 2 diabetes and heart disease - Study

A new study has found that night owls may be at higher risk for heart disease and type 2 diabetes compared to early birds.

If you prefer to go to bed late and get up later – you are a sleep chronotype known as being a night owl.

Scientists have found that fat builds up more easily in night owls and their bodies are less able to burn fat for energy.

Night owls are also supposedly more likely to be insulin-resistant, which means their muscles require more insulin to be able to get the energy they need.

According to the study published in the journal Experimental Physiology, night owls were found to be more sedentary – they also had lower aerobic fitness levels and burned less fat at rest and while active in comparison to the early birds in the study.

But on the other hand, those who wake up early, and rely more on fat as an energy source were found to be often more active during the day, than those who stayed up later.

Therefore, the findings may help explain why night owls are at greater risk of type 2 diabetes and cardiovascular disease.

It may also help doctors to identify patients early on who are more likely to develop the conditions.

With regard to the findings, Prof Steven Malin, a senior author on the study and expert in metabolism at Rutgers University in New Jersey is reported to have said, “This could help medical professionals consider another behavioural factor contributing to disease risk.”

Additionally, research suggests “later cronotypes have higher body fat located more in the stomach or abdominal region, an area which many health professionals believe to be worse for our health,” Malin said.

He adds, “Insulin tells the muscles to be a sponge and absorb the glucose in the blood. Think about it like water from a water faucet: You turn the water on and a drop touches the sponge and is immediately absorbed.

“But if you’re not exercising, engaging those muscles, it’s like if that sponge was to sit for a couple of days and get rock hard. A drop of water isn’t going to make it soft again,” he said.

If sleep chronotype is affecting how our body uses insulin and impacts metabolism, then being a night owl might be useful in predicting a person’s risk for heart disease and type 2 diabetes, Malin states.

Writing in Experimental Physiology, the team notes that early birds were found to be more sensitive to blood levels of the hormone insulin and burned more fat than night owls while at rest and during exercise.

Additionally, the night owls were found to be less sensitive to insulin, and also their bodies favoured carbohydrates over fat as an energy source.

However, differences in metabolism between early birds and night owls seem to be unclear to the researchers.

But Malin believes that one possibility could be a mismatch between the time people go to bed and get up the next morning, and the circadian rhythms that govern their body clocks.

He is quoted as saying, “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, but most notably among adults would be work.”

For instance, night owls may prefer to go to bed late but may still have to get up early in the morning to go to work or to take care of children - this may cause them to be out of alignment with their body clocks when they would rather be sleeping.

We all have a circadian rhythm – an internal 24-hour body clock that regulates the release of the hormone melatonin to promote sleep. The production of the hormone ceases so that we can wake up.

Our body clock also regulates our hunger, when we feel most sluggish, and when we feel energetic enough to exercise, among many other bodily functions.

Dr Phyllis Zee, director of the Center for Circadian and Sleep Medicine at Northwestern University Feinberg School of Medicine in Chicago, who was not involved with the research and who is also a professor of neurology reportedly said, “The study adds to what we know.”

He also reportedly said, “There is good evidence that being a late sleeper has been linked to a higher risk for metabolic and cardiovascular disease.

“Several mechanisms have been proposed: sleep loss, circadian misalignment, eating later in the day and being exposed to less morning light and more evening light, which have all been shown to affect insulin sensitivity.”

In conclusion, Malin said, “If we promote a timing pattern that is out of sync with nature, it could exacerbate health risks. “Whether dietary patterns or activity can help attenuate these is an area we hope becomes clear in time.”