Night shift schedules threaten waistline

Employees such as nurses and CNAs who work overnight are likely burning less energy than those on a normal schedule, putting them at increased risk for obesity, according to new study results.

Researchers have known that people who work and eat overnight — when their bodies are biologically prepared to sleep — are prone to weight gain. The reasons why aren't clearly understood.

A study published in the Proceedings of the National Academy of Sciences found that total daily energy used by participants decreased when they were put on a shift-work schedule.

Fourteen adults spent two days following a sleep-at-night, stay-awake-during-the-day schedule. Then their routines were reversed for three days. The timing of their meals changed but total calories didn't.

Workers probably burned fewer calories because their activities and their circadian clocks were misaligned, said senior author Kenneth Wright,  Ph.D., the director of CU-Boulder's Sleep and Chronobiology Laboratory.

“Shift workers never adapt,” Wright said. “What we can say is that it's perhaps even more important to have a healthy diet for shift workers as well as a healthy amount of physical activity.”