Workaholics are more likely to have an underactive thyroid, known as hypothyroidism, according to a new study. Hypothyroidism was twice as common in people working more than 53 hours a week, compared with those working 36 to 42 hours a week the equivalent of a full-time 9-5 profession.
An underactive thyroid has been linked to several health concerns, including heart disease and diabetes. Hormones produced by the thyroid are crucial in controlling heart function, digestion muscle control, brain development, and bone maintenance.
Underactive Thyroid Causes and Treatment
The researchers are unsure what it is about long working hours that could lead to the condition and hope further research can shed light on the correlation. ‘Overwork is a prevalent problem threatening the health and safety of workers worldwide,’ said principal investigator Young Ki Lee at the National Cancer Center in Goyang-si, South Korea.
‘To our knowledge, this study is the first to show that long working hours are associated with hypothyroidism.’ Researchers found a higher risk of hypothyroidism in people who worked long hours regardless of their socioeconomic status or sex.
The researchers used the data of 2,160 adult full-time workers who participated in the Korea National Health and Nutrition Examination Survey from 2013 to 2015. Hypothyroidism occurred in 3.5 percent of subjects who worked 53 to 83 hours a week compared with 1.4 percent of those who worked 36 to 42 weekly hours.
A working week of between 53 to 83 hours equates to somewhere between 10.5 and 16.5 hours of work a day if working five days a week. Further studies are now needed to find out whether long working hours cause hypothyroidism, which is a known risk factor for heart disease and diabetes, the team said.
‘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,’ said Professor Lee. ‘Additionally, screening for hypothyroidism could be easily integrated into workers’ health screening programs using simple laboratory tests.’
There are likely multiple factors linking long working hours and hypothyroidism that have not yet been studied in-depth, Professor Lee said. ‘Long working hours contribute to psychological stress, and rat models have shown that social, as well as physical chronic stress, reduced thyroid hormone levels,’ he said.
‘Overwork-related unhealthy metabolic conditions and physical inactivity may be another cause of hypothyroidism. Subclinical hypothyroidism is prevalent among patients with obesity.’ Because South Korea passed a law in 2018 that reduced the maximum number of working hours from 68 to 52 per week, a fall in hypothyroidism cases could be an important indicator in future studies.
‘If long working hours really cause hypothyroidism, the prevalence of hypothyroidism in Korea might decrease slightly as the working hours decrease,’ Lee said. In the UK, employees can’t work more than 48 hours a week on average, with some exceptions based on industry.
However, employees can choose to opt-out of the rule and choose to work more than 48 hours a week. About 2 percent of the UK population has hypothyroidism, which is about 10 times more common in women, according to the British Journal of General Practice. dailymail