Night owls may have a higher risk of suffering from heart disease and type 2 diabetethan early risers, a first-ever study from the U.K. finds.
Dr. Suzana Almoosawi, who led the study, says that your genes, ethnicity, and gender determine the likelihood of you being a morning or evening type.
In adulthood, being an evening type is associated with greater risk of heart disease and type 2 diabetes, and this may be potentially due to the poorer eating behavior and diet of those people.
“Our review also found that people who have a poorer control of their diabetes are more likely to be evening types,” she added.
What Is It About Night Owls?
The researchers found increasing evidence from studies linking conditions such as heart disease and type 2 diabetes to people with a natural preference for evenings.
They found people who go to bed later tend to have unhealthier diets, consuming more alcohol, sugars, caffeinated drinks, and fast food than early risers.
They consistently report more erratic eating patterns as they miss breakfast and eat later in the day.
Their diet contains fewer grains, rye and vegetables and they eat fewer, but larger, meals.
They also report higher levels of consumption of caffeinated beverages, sugar, and snacks, than those with a morning preference, who eat slightly more fruit and vegetables per day.
This potentially explains why night owls have a higher risk of suffering from chronic disease, according to Almoosawi and her team.
Why The Link To Diabetes?
Eating late in the day was also found to be linked to an increased risk of type 2 diabetes because the circadian rhythm influences the way glucose is metabolized in the body.
Glucose levels should naturally decline throughout the day and reach their lowest point at night.
However, as night owls often eat shortly before bed, their glucose levels are increased when they are about to sleep. This could negatively affect metabolism as their body isn’t following its normal biological process.
One study showed that people with an evening preference were 2.5 times more likely to have type 2 diabetes than those with a morning preference.
This also impacts on people who work shifts – particularly rotating shifts – as they are constantly adjusting their body clock to fit with their working hours.
The researchers found that this reduces their sensitivity to insulin and affects their glucose tolerance, putting them at greater risk of developing type 2 diabetes.
Other Interesting Findings
People’s preferences to rising early and going to bed later change at varying points in the life cycle.
The morning chronotype is more common in children and can appear when a baby is just three-weeks-old.
This changes during childhood. While over 90% of two-year-olds have a morning preference, this declines to 58% by the age of six and shifts further towards an evening preference during puberty.
This evening preference continues until an adult reaches their early 50’s and they then begin to revert back to a morning preference.
The review, according to Almoosawi, has highlighted a major gap in our understanding as to how our biological clock affects food intake in infants, children and the elderly.
Ethnicity and society can also influence your chronotype.
For example, studies have revealed that Germans are more likely to have an evening preference in comparison to Indians and Slovakians.
There can also be differences between people living in urban and rural areas in the same country.
The review has called for more studies in the general population that define people’s body clock and how this relates in the long-term to their dietary habits and health.