About half a million Canadian workers experience depression, and most say it interferes with their ability to manage their jobs, Statistics Canada reported Friday.

Data from 2002 showed almost four per cent of workers between the ages of 25 and 64 reported being depressed in the previous 12 months before the survey. The report used an accepted international survey technique to measure depression.

Nearly 80 per cent of them said the symptoms adversely affected their work, according to the Canadian Community Health Survey called "Depression and work impairment."

Job-related factors associated with depression included:

• Night shifts.
• Non-regular hours.
• Work stress.
• Occupation.

The prevalence of depression was relatively high among workers who spent fewer than 30 hours on the job. It was lower among those who worked more than 40 hours.

Workers in sales or service and those in white-collar jobs were more likely than blue-collar workers to have experienced depression.

About 13 per cent of workers who had experienced depression reported at least one day in the previous two weeks when they had to stay in bed, or cut down on normal activities, or their daily activities took extra effort, because of emotional or mental health or the use of alcohol or drugs.

Workers who were depressed reported an average of 32 days in the previous year when their symptoms left them unable to either carry out normal activities or work. 

Hiding symptoms from fear 

Sarah Hamid-Balma said she went through a major depression after graduating from university that interfered with her ability to work.

"In the workplace it affected mostly my concentration," said Hamid-Balma of Vancouver. "I was struggling with a lot of physical symptoms, having headaches and stomach aches. Anyone who has had a cold in the workplace knows how that interferes with getting work done."

She concealed her depression, a common occurrence among those who fear the illness will lead them to be edged out of the workplace. Hamid-Balma now has a supportive employer, working as director of education and communications with the Canadian Mental Health Association in B.C.

Stressed, depressed

People who described most days at work as stressful were more likely to report a depressive episode in the previous year compared with those reporting less stress. Earlier research showed a similar relationship between work stress and psychological disorders.

Over a two-year period, workers who had a depressive episode were 1.8 times more likely to have taken at least one disability day in the previous two weeks.

In recent years, productivity experts have suggested the cost to the Canadian economy from days lost to depression and from those on the job not being able to perform their best may be exceeding $3 billion each year.