Could long hours at the office put you at risk for hypothyroidism?
New research suggests it's possible: Hypothyroidism (an underactive thyroid) was more than twice as common in adults who worked 53 to 83 hours a week as in those who worked 36 to 42 hours a week (3.5% vs. 1.4%).
Hypothyroidism can cause tiredness, depression, feeling cold and weight gain, and it's also a risk factor for heart disease and diabetes.
In this study, researchers analyzed data from 2,160 adult full-time workers in South Korea. Records of blood work done on the workers allowed researchers to identify hypothyroidism.
For each 10-hour increase in the work week, people who worked longer hours had a higher risk of hypothyroidism than those who worked 10 hours less, according to the study published March 31 in a special supplemental section of the Journal of the Endocrine Society.
Hypothyroidism affects women more often than men, but the researchers found that long working hours was associated with an increased risk of hypothyroidism regardless of the workers' sex or socioeconomic status.
Further research is needed to determine whether long working hours actually cause hypothyroidism, said study principal investigator Dr. Young Ki Lee, from the National Cancer Center in Goyang-si, South Korea.
"If a causal relationship is established, it can be the basis for recommending a reduction in working hours to improve thyroid function among overworked individuals with hypothyroidism," Lee said in a journal news release.
"Additionally, screening for hypothyroidism could be easily integrated into workers' health screening programs using simple laboratory tests," he noted.
"Overwork is a prevalent problem threatening the health and safety of workers worldwide," Lee said. "To our knowledge, this study is the first to show that long working hours are associated with hypothyroidism." The study only found associations, not a cause-and-effect link.
In 2018, South Korea passed a law restricting the maximum number of working hours from 68 to 52 a week.
"If long working hours really cause hypothyroidism, the prevalence of hypothyroidism in Korea might decrease slightly as the working hours decrease," Lee said.