A new study has claimed that people who tend to stay up late are not at a higher risk due to their habit, but because of associated lifestyle factors. The research, conducted in Finland, looked at 37-year data of more than 23,000 people to determine whether being a night owl directly affects the risk of dying within the next few decades. Previous studies had suggested people who tend to sleep late have a higher mortality risk and tendency to prefer riskier behaviour.
The new findings were published on Friday in the journal Chronobiology International.
The 37-year follow-up period ended in 2018, and more than 8,700 participants died during this time. They were given a questionnaire and asked to state whether they were "clearly a morning person," "to some extent a morning person," "clearly an evening person" or "to some extent an evening person."
The research found that people who responded that they are "clearly" evening people were at 21% higher risk of death from any cause compared to those who were "clearly" morning people.
But when the researchers ran a second analysis after adding factors like body mass index (BMI), self-reported sleep duration, educational level, rates of chronic diseases, alcohol consumption and smoking status and quantity - rather than age and sex - they found that the night owls' excess mortality risk dropped to just 9%.
"It's not about the chronotype (being a morning or evening person) itself that is dangerous, but it is the associated lifestyle factors," study co-author Jaakko Kaprio, a professor of genetic epidemiology at the University of Helsinki in Finland, told Live Science.
"This can reassure people concerned about what being a morning or evening person means for their life expectancy and health," the expert further said.
The new research further showed that rates of death due to alcohol-related diseases and accidental alcohol poisoning were 92% higher among "clearly" evening people compared with "clearly" morning people.
