Experts have warned that night owls are at greater risk of developing type 2 diabetes because their biological clock is out of sync with that of society.
It is already known that those who stay up late and are more active at night are more likely to smoke, eat unhealthy foods and have a higher body mass index, all factors linked to this condition.
However, the increased risk of diabetes may not be due to lifestyle alone, the researchers said.
Instead, they suggest the link could also be because an owl’s biological clock may be out of sync with that of the rest of society.
A team from Leiden University Medical Center (Netherlands) analyzed the sleep schedule, waist circumference and BMI of more than 5,000 people.
Experts warn that night owls are at a higher risk of developing type 2 diabetes because their biological clock is out of sync with that of society. Pictured: Stock image of a security guard
Researchers suggest the link could also be because a night owl’s biological clock may be out of sync with the rest of society (file image)
Of the group, 1,576 underwent MRI scans to measure visceral and liver fat, while electronic medical records were used to verify how many people had type 2 diabetes.
Patients were classified into three groups, or “chronotypes,” based on their sleep schedule: late, early, and intermediate.
Lead researcher Dr Jeroen van der Velde said: ‘Previous studies have indicated that a late chronotype (preferring to go to bed late and wake up later) is associated with an unhealthy lifestyle.
‘Late chronotypes are more likely to smoke or have an unhealthy diet, for example, and it has been suggested that this is why they are at higher risk of obesity and metabolic disorders, including type 2 diabetes.’
The group was followed for an average of 6.6 years, during which 225 patients were diagnosed with type 2 diabetes.
Taking into account age, sex, total body fat and lifestyle factors such as exercise, diet and smoking, the study found that people who preferred to stay up late still had a 46 percent higher risk of type 2 diabetes than people in the middle group.
Dr van der Velde suggested there may be “other mechanisms at play” outside of lifestyle.
Researchers also found that night owls tended to have a higher BMI, larger waist circumference, more visceral fat and higher liver fat content (file image)
“A likely explanation is that the circadian rhythm or biological clock in late chronotypes is not synchronized with the work and social schedules that society follows,” he said.
“This can lead to circadian disruption, which we know can lead to metabolic disorders and ultimately type 2 diabetes.”
The researchers also found that night owls tended to have a higher BMI, larger waist circumference, more visceral fat and higher liver fat content.
Dr van der Velde added: ‘People with a late chronotype are probably more likely to eat later in the evening.
‘While we didn’t measure this in our study, there is growing evidence that time-restricted eating – that is, not eating anything after a certain time, such as 6 p.m. – can have metabolic benefits.
‘Night owls who are concerned about the increased risk of type 2 diabetes might want to try this, or at least try to refrain from eating late at night.
“We don’t have proof yet, but over time we aim to offer specific advice on the right time to adopt lifestyle habits.”
The study will be presented at the annual meeting of the European Association for the Study of Diabetes in Madrid.
