Working long hours damages employees’ brain function and is as bad as smoking as a risk factor for dementia.
Researchers from University College London and the Finnish Institute of Occupational Health (FIOH) say that results clearly indicate that working overtime can reduce wellbeing and cognitive function of employees.
In what is the largest study of its kind, the researchers monitored 2,214 middle-aged UK civil servants. The employees took various cognitive tests in 1997-99 and again in 2002-04.
In the first set of tests, employees working more than 55 hours a week performed worse in vocabulary tests than employees working 35-40 hours a week. In the follow-up tests five years later, those working longer hours again performed worse at vocabulary tests, but also had declined scores in cognitive reasoning.
The effects were cumulative. The longer the working week, the worse the test results. Employees with long working hours also had shorter sleeping hours, reported more symptoms of depression and used more alcohol than those with normal working hours.
Reporting their findings in the American Journal of Epidemiology, the researchers said: “The link between cognitive impairment and dementia later in life is clearly established. The difference between staff working long hours and those working normal hours is similar in magnitude to that of smoking, a risk factor for dementia.”
While working hours in the UK are falling, more than one-fifth of workers in the UK work 45 hours a week or more, according to the Office for National Statistics.