Night work linked to obesity in new study

A new study has discovered that night work and shift patterns disrupt the employee’s metabolism, causing them to expel less energy than they normally would over the course of a day.

This effect was found to be particularly pronounced when employees tried to sleep during the day. Despite the fact that they typically had more disturbed sleep, employees who slept during the day burned between 12 and 16% fewer calories than those who slept at night.

These findings could help to explain previous links found between night shift workers and higher risk of health problems like heart disease, diabetes and stroke.

Director of the sleep and chronobiology laboratory at the University of Colorado, Dr Kenneth Wright, said that the lower energy could accentuate the poor diets and lack of physical activity often seen in night workers. He reasoned that this may be down to a mishmash between the internal body clock and sleep patterns that is disturbing the metabolism.

“Specifically, the 52-59kcal lower total daily energy expenditure on night shifts, if recurrent without a reduction in food intake, would contribute to weight gain.

“As little as 50 kcal excess calorie storage per day can increase weight over time and if increased exhaustion and fatigue levels associated with shift work results in reduced physical activity levels, this would promote weight gain.”

In this study (which was published in the journal Proceedings of the National Academy of Sciences) 14 adults were put through a simulated day shift and night shift working pattern over a six-day period. Researchers analysed the energy use, nutrient use and hormone levels of the participants, alongside their sleeping patterns.

It was found that energy use increased 4% on the first night shift and then fell to around 3% on the following two days when compared to day shift patterns. Dr Wright pointed out that more research would be needed to establish how rotating shift patterns and additional night shifts could further affect the metabolism.