Late sleepers are at a greater risk of premature death compared to early risers, a study has found.
Research involving 433,000 Britons aged 38 to 73 revealed night owls had a 10% higher mortality risk, regardless of the cause.
The study also observed among late sleepers a higher prevalence of mental illness, diabetes, and brain, breathing and abdominal disorders.
The paper was published in scientific journal Chronobiology International on Wednesday.
Participants were defined as definite morning types, moderate morning types, moderate evening types and definite evening types, and were assessed over a six-year period.
Co-author Dr Kristen Knutson said employers should adapt to workers’ natural sleeping patterns to boost their productivity and preserve their health.
The sleep researcher from Northwestern University in Chicago, said: "Night owls trying to live in a morning lark world may have health consequences for their bodies.
“Those who struggle with early mornings should be given later start times at work
"They shouldn't be forced to get up for an 8am shift. Make work shifts match people's chronotypes. Some people may be better suited to night shifts."
Test subjects who worked outside of their natural rhythm experienced impaired metabolism, mood changes and “social jetlag”, when they would rise later from bed on their days off.
Theories as to why night owls risked an early death included risks associated with changes in behavior and the body. Greater exposure to artificial light was also raised as an issue which “acutely” reduces melatonin production, a hormone that alerts the body when it is time to sleep and wake up.
“Lower levels of melatonin have been associated with greater insulin resistance, increased risk of diabetes and breast and prostate cancer,” the paper states.
British co-author Malcolm von Schantz, a professor at the University of Surrey, said the paper highlighted "a public health issue” concerning natural night owls “that can no longer be ignored.”
He added: "We should discuss allowing evening types to start and finish work later, where practical. And we need more research about how we can help evening types cope with the higher effort of keeping their body clock in synchrony with sun time."