Shift Work and the Body Clock

WORKING AGAINST THE CLOCK: THE HEALTH EFFECTS OF SHIFT WORK A. Nurses, factory workers, truck drivers and emergency responders are among the many Canadians whose jobs require them to be awake while most people sleep. Shift work keeps hospitals, transit systems and power plants running around the clock, and for some workers it brings real benefits, such as higher pay, quieter commutes and free time during daylight hours for appointments or child care. Yet researchers have long been interested in how working at night affects the body, because humans evolved to be active during the day and to rest in the dark. Across the country, a large share of the workforce works outside the standard nine-to-five day at least some of the time. B. At the centre of this question is the body's internal clock, a small group of cells in the brain that keeps a roughly twenty-four-hour rhythm. This clock responds mainly to light. Morning light signals the body to become alert, while darkness triggers the release of melatonin, a hormone that prepares the body for sleep. When a person works through the night and then tries to sleep in the morning, the clock receives confusing signals. Daytime sleep tends to be shorter and lighter, and many night workers build up a sleep debt over the course of a week that a single day off cannot fully repay. Exposure to bright light on the drive home in the morning can make the problem worse, because it tells the brain that the day has begun. C. The effects of this disruption go beyond simply feeling tired. Studies of long-term shift workers have linked irregular schedules to digestive problems, weight gain and a higher risk of certain heart conditions, although scientists stress that the causes are complex and that diet, stress and exercise also play a part. Fatigue affects safety as well. Reaction times slow in the early hours of the morning, which is why the drive home after a night shift is considered one of the riskiest parts of the job. Long-term fatigue can also affect mood, and some workers report feeling cut off from friends and family whose schedules run in the opposite direction. D. Workers and employers can take steps to reduce the harm. Experts often suggest that schedules rotate forward, moving from day shifts to evening shifts to night shifts, because the body adjusts more easily to a later bedtime than to an earlier one. At home, blackout curtains, earplugs and a consistent sleep routine can make daytime rest more effective, and family members can help by keeping the house quiet. Some workplaces now provide brightly lit break rooms to help night staff stay alert, and a few allow short planned naps during long shifts. No single strategy solves the problem, but together they can make a demanding schedule easier to live with.