BEHIND THE HEADLINES WITH DR TIM CROWE
Whether night-shift work is a necessity or a lifestyle choice, the altered sleep patterns that go with it can wreak havoc on your health.
Is your job making you fat? Research links shift work with poor health
Shift work is becoming increasingly popular because of the high and growing demand for workplace flexibility and productivity in modern society. The flexibility of shift work brings with it a downside, however. A swelling pool of research links it with adverse health problems that include obesity and metabolic conditions like diabetes.
The latest research
A recent scientific review has zeroed in on the strength of the link between shift work and the prevalence of obesity. ‘Shift work’ was said to occur when the employee regularly switched between daytime and overnight schedules, or worked exclusively overnight shifts. The review investigated 28 studies that put the health impact of shift work under the microscope.
It found the link between shift work and obesity was strong, with the permanent shift workers experiencing up to 30 per cent higher risk of obesity than other workers. These permanent shift workers were more likely to gain excess weight compared to workers who alternated between day and night shifts. This pointed to ongoing disruption of normal night sleep patterns being particularly harmful, the study said.
The review also found that the biggest worry was not primarily weight gain in general — it was where the weight was going to. It turned out that people who routinely worked the graveyard shift accumulated more dangerous abdominal fat.
Out of sync
Shift work challenges your body’s natural circadian rhythm, a 24–hour internal clock which regularly transports you between sleepiness and alertness. Shift work creates a misalignment between your internal clock and the outside world. This can cause your body to secrete drowsiness-inducing chemicals when you’re working, or make you alert and awake when you’re trying to sleep. Exposure to bright lights during the night intensifies the problems caused by shift work. Light exposure suppresses the production of the sleep hormone called melatonin. Melatonin is known to play a key role in regulating hormones such as insulin, cortisol and leptin.
Researchers have conducted sleep laboratory experiments over five weeks where people had their sleep patterns disrupted and were slowly shifted to daytime sleeping and nighttime waking to mimic shift work. The reversal of the circadian rhythm caused a drop in their metabolism. That’s bad news for long-term weight gain. Those in the experiment also saw their insulin fall by a third — making them less able to control their blood glucose levels.
What can we do?
Shift work challenges healthy eating habits and discourages you from exercising regularly. Shift workers should be even more aware of this than others.
One way to tackle the healthy eating problem is to take healthy foods and snacks to work — and not rely on the limited options available during nighttime hours.
Employers also need to accept some level of responsibility and be flexible with schedules. They should avoid exposing any single employee to long-term night-shift work.