In the ongoing flap about whether it’s better to be a night owl or an early bird, new evidence suggests that nocturnal navigators are nearly 50% more likely to develop Type 2 diabetes than those who quickly call it a night.
Darkness dwellers have a late chronotype, which means they prefer to go to bed late and wake up late. This behavior has been linked to a greater likelihood of tobacco use and unhealthy eating habits, putting them at risk of obesity and Type 2 diabetes, a chronic metabolic disease.
“However, we believe that lifestyle cannot fully explain the relationship between a late chronotype and metabolic disorders,” said Jeroen van der Velde, a researcher at Leiden University Medical Centre in the Netherlands.
“In addition, while it is known that a late chronotype is associated with high [body mass index], it isn’t clear to what extent chronotype affects body fat distribution,” van der Velde added.
His team studied the association between sleep timing, diabetes and body fat distribution in more than 5,000 people enrolled in the Netherlands Epidemiology of Obesity study.
Volunteers, who were mostly in their mid-50s, shared their typical wakeup and bedtimes.
Participants were divided into three groups — early chronotype (the 20% of participants with the earliest bedtimes), late chronotype (the 20% of participants with the latest bedtimes) and intermediate chronotype (the remaining 60%).
The participants were tracked for nearly seven years — during that time, 225 were diagnosed with Type 2 diabetes.
After adjusting the results for age, sex, education, total body fat and lifestyle factors such as physical activity, diet quality and alcohol consumption, the researchers determined that participants with a late chronotype had a 46% higher diabetes risk than those with the intermediate chronotype.
The results show that the increased diabetes risk for late chronotypes can’t be blamed just on lifestyle, van der Velde said.
“A likely explanation is that the circadian rhythm or body clock in late chronotypes is out of sync with the work and social schedules followed by society,” he reasoned. “This can lead to circadian misalignment, which we know can lead to metabolic disturbances and ultimately Type 2 diabetes.”
Van der Velde’s team expected early chronotypes to have a similar diabetes risk as intermediate chronotypes — they found early birds actually had a slightly higher risk but “this was not statistically significant.”
The researchers also found that late chronotypes had a higher BMI, larger waist circumference, more visceral fat — harmful fat wrapped around internal organs — and higher liver fat content compared to those with an intermediate chronotype.
“People with a late chronotype appear to be at greater risk of developing Type 2 diabetes compared to those with intermediate chronotype, possibly because of higher body fat including more visceral fat and liver fat,” van der Velde said.
“The next step is to study if those with a late chronotype improve in metabolic health when they make changes in the timing of their lifestyle habits,” he added.
Night owls should consider stopping eating at a certain time, such as 6 p.m., van der Velde said, because the timing of meals can affect digestion and metabolism.
“The evidence isn’t there yet but, in time, we aim to provide specific advice regarding the timing of lifestyle behavior,” van der Velde said.
His findings — which will be presented this week at the annual meeting of the European Association for the Study of Diabetes — follow recent research that suggests that being a night owl could be good for your cognitive function and bad for your mental health.
Dr. Mitchell Roslin, chief of bariatric and metabolic surgery at Northern Westchester Hospital and Lenox Hill Hospital, said poor sleep habits make obesity and diabetes more likely and lead to higher release of stress hormones such as cortisol.
“Cortisol and stress further increase glucose levels and promote weight gain,” Roslin, who is not involved in the new study, told The Post. “Weight gain increases the chance of sleep apnea and insulin resistance. It is easy to see the ball running downhill.”