Intro to Shift Work Disorder

The graveyard shift has been associated with everything from depression to cancer. Shift work disorder, applies to people who suffer insomnia and sleepiness from working nights. It has been blamed for ulcers and heart disease.

"It's not surprising," said Dr. Louis Ptacek, a UCSF neurologist studying sleep behaviors. "We evolved on a planet that is rotating every 24 hours. Our internal clock is more than just when we sleep and wake. It's related to cell division and it regulates our immune systems. When we battle our internal clock, that has complications."

15 million people, 15 percent Americans, work a night shift, according to the U.S. Department of Labor. Studies show that 10 - 20 percent of shift workers have trouble with insomnia and feeling sleepy on the job.

People who are sleep-deprived can succumb to "microsleeps," where they fall asleep for a few seconds and don't realize it, said Dr. Clete Kushida, director of the Stanford University Center for Human Sleep Research.

"Probably the most obvious problems with (night) shift work are cognitive functions, so people have difficulty focusing. They might have problems with irritability and mood fluctuations," Kushida said. "And then there is excessive sleepiness, which can lead to motor vehicle accidents and industrial accidents."

Last December, the International Agency for Research on Cancer, listed the graveyard shift as a "probable" cause of cancer. The agency's conclusion followed several studies that show high rates of cancer - breast cancer - among people working night shefts.

ScienceDaily (Mar. 18, 2008) — Chronic sleep disruption can cause heart and kidney disease, researchers at the Peter Munk Cardiac Centre of the Toronto General Hospital have discovered.

“Disrupted circadian rhythms have a devastating effect on the heart, kidney and possibly other organs,” says Dr. Michael Sole, Cardiologist at the University of Toronto. “This is the first study of its kind to demonstrate that sleep cycle disruption actually causes heart and kidney disease.”

“Shift workers and flight-crews might want to consider these findings when scheduling work time,” suggests Dr. Sole, adding that these workers could try to maintain a constant working schedule for one month or more, allowing the body to readjust its clock to external cues.