Report of air traffic controllers caught sleeping on the job has been a hot topic in the United States, but they're not the only ones who battle fatigue on the job.

Research has shown that many professions have to battle sleep deprivation, including truck drivers, emergency responders, physicians and others who work night shifts.

Colin Shapiro, a senior scientist at University Health Network, and director of the Sleep & Alertness Clinic & Sleep Research Laboratory at Toronto Western Hospital says plenty of research has shown that trying to function without enough sleep affects our ability to focus and pay attention.

"And while we sometimes think we can plow through it, the reality is you can't," he told Canada AM Wednesday.

Shapiro says studies have shown that truck drivers who drive for 17 hours have the reaction times of someone with a 0.5 per cent blood alcohol level.

"Driving for 22 hours puts you at the legal limit in terms of your ability to perform. So it's like driving impaired when you've been driving for 22 hours," he said.

The effects of sleep deprivation might not always be felt the first day but they can accumulate, says Shapiro. So a worker may be not be functioning as well at the end of the week as they did on Monday if they're consistently getting less sleep than they need .

To some extent, people can make up their sleep loss on the weekend, says Shapiro. "But not entirely. And so people who are chronically short of sleep or who sleep less than they need to end up living shorter lives and with more health problems," he says.

Indeed, back in 2007, the International Agency for Research on Cancer, the cancer arm of the World Health Organization, found that that night shift work is so hard on the body that they deemed it a "probable carcinogen" to humans.

The IARC said it reviewed dozens of studies linking night work and breast cancer. One of the studies, published in the Journal of the National Cancer Institute, showed a 36 per cent greater risk of breast cancer for women who had worked night shifts for more than 30 years, compared with women who had never worked nights.

They also cited more than 20 studies on lab rats that found an increased tumour rate among rats that were exposed to constant light, dim light at night, and simulated chronic jet lag.

It's thought that because night workers are forced to sleep during the light of day, their circadian rhythms are disrupted and they don't get the kind of restorative sleep that they would if they slept at night.

Another study released last year by researchers at the University of British Columbia found that workers on night shifts and rotating shifts were almost twice as likely to be injured on the job than those working regular day shifts.

The study authors noted that the number of Canadians working non-regular hours had increased dramatically in recent years. The number of women in rotating and night shift work increased by 95 per cent between 1996 and 2006, primarily in the health care sector. For men, the increase was 50 per cent, mostly in manufacturing and trades.

This week, perhaps in a sign of growing awareness of the problem of sleep deprivation, the Federal Aviation Administration announced it would be changing air traffic controllers' work schedules. Controllers will now get an extra hour off between shifts, so that they have at least nine hours off between shifts, compared with the eight currently mandated.

That decision came after the FAA reported another incident in which a controller fell asleep while on duty early Saturday morning at a busy Miami regional facility. That followed at least two other high-profile incidents of air traffic controllers falling asleep at the switch.

It's unclear whether nine hours between shifts will be enough for the controllers. Shapiro says the amount of sleep that people need varies from person to person. He says the average amount of sleep adults require is seven to eight hours. But some can function perfectly fine with less. Factors such as one's age, the amount of life stress one contends with and even climate can come into play.

And while many of us assume that if less sleep is bad, more sleep must be better, that's not quite true either. Shapiro points out that oversleeping can affect longevity, too.

"So you have to tailor it so you're functioning well. The problem is that sometimes your own perception of your functioning isn't brilliant," he says.