Loads of Overtime May Cost You Your Head
Logging More Than 55 Hours a Week on the Job Takes a Mental Toll on Middle-Aged Workers, Study Shows
Jan. 9, 2009 -- Your productivity-obsessed boss might not like this: A new
study shows that middle-aged people who labor for very long hours have lower
scores on mental function tests.
The study, published in the American Journal of Epidemiology,
involved analyzing the performance of 2,214 middle-aged British civil servants
on a battery of thinking tests given in two time periods from 1997 to 2004.
The workers were given cognitive tests, and those who worked more than 55
hours per week scored lower on vocabulary and reasoning exams than people whose
work weeks lasted 40 hours at most, the researchers report.
Long working hours were predictive of lower reasoning and lower vocabulary
scores on follow-up tests at the end of the study period.
The results held true regardless of age, sex, marital status, education,
occupation, income, physical diseases, psychosocial factors, sleep disturbances, and health
risk behaviors, the researchers report.
"This study shows that long working hours may have a negative effect on
cognitive performance in middle age," the researchers conclude.
Study lead author Marianna Virtanen, MD, of the Finnish Institute of
Occupational Health in Helsinki, notes that long working hours are common
worldwide and that up to 17% of employees in the European Union worked overtime
"Long working hours have been found to be associated with cardiovascular
and immunologic reactions, reduced sleep duration, unhealthy lifestyle, and
adverse health outcomes," the authors write.
There's also increasing evidence that such midlife risks may play a role in
later dementia, they write.
Long hours have been found to negatively affect cognitive performance,
grammatical acumen, and alertness, the researchers say.
The study examined the relationship between working long hours and cognitive
function over a five-year follow-up period.
"Compared with employees working 40 hours or less per week, employees
working more than 55 hours had lower vocabulary scores," the authors write.
"At follow-up, they had lower scores also on the reasoning test."
People working more than 55 hours per week scored lower on two of five
cognitive function measurements, the researchers report.
"Decline in cognitive function has already been shown to be present
among the middle-aged," the researchers write. "As mild cognitive
impairment predicts dementia and mortality, the identification of risk factors
for mild cognitive impairment in middle age is important."
The study's findings are significant, researchers say, because long hours
may lead to cognitive impairment in middle-aged people similar in
magnitude to smoking, a known risk factor for