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.
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, though. A swelling pool of research links it with adverse health problems that include obesity and metabolic conditions such as diabetes.
The latest research
A 2017 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 with 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 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 that 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 melatonin. Melatonin plays 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 night-time 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 need to 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 at night.
Employers also need to accept some level of responsibility by being flexible with schedules and avoiding exposing any single employee to long-term night-shift work.
Five tips to stay on top of shift work
- Batch cook meals, so you have healthy food to take to work and to eat when you get home.
- Have your main meal before you set out for work.
- Choose to eat smaller meals and snacks during work.
- Put exercise in your diary – like an appointment.
- Limit screen time before bed, as this disrupts sleep.
Article sources and references
- Morris CJ et al. 2015. Endogenous circadian system and circadian misalignment impact glucose tolerance via separate mechanisms in humans. PNAS 112:E2225-34https://www.pnas.org/content/112/17/E2225
- Sun M et al. 2017. Meta-analysis on shift work and risks of specific obesity types. Obesity Reviews 19:28-40https://www.ncbi.nlm.nih.gov/pubmed/28975706