The study – first published in the journal BMC Public Health – looked at data from 133,608 Korean men and women aged between 40 and 69 years old over a nine-year period. The participants were placed into four categories: those who slept less than six hours a night, between six and eight hours, between eight and 10 hours or more than 10 hours.
The result? Men who got the least amount of shut-eye were more likely to develop metabolic syndrome (a term that refers to a number of conditions, including increased blood sugar levels, high cholesterol levels and high blood pressure,) while both genders in this group had a greater chance of having excess fat around their middle.
And while you wouldn’t be alone in thinking that more sleep would lead to better benefits, the research proved quite the opposite.
All participants who slept for more than 10 hours a night increased their risk of metabolic syndrome, while the women were found to have larger waist circumferences.
“This is the largest study examining a dose-response association between sleep duration and metabolic syndrome and its components separately for men and women,” explained Claire E. Kim, the study’s lead author.
“We observed a potential gender difference between sleep duration and metabolic syndrome, with an association between metabolic syndrome and long sleep in women and metabolic syndrome and short sleep in men.”
There was one caveat though: because the research was purely observational, the researchers weren’t able to determine the cause and effect of the findings.