People who work outside a traditional nine-to-five schedule are more likely to be overweight, experience sleeping problems and may even have an increased risk of developing diabetes, a new study has found.

According to US researchers, the potential health effects of shift work have become a major concern in recent years because of our increasing 24/7 society. More and more people are now working hours outside of the nine-to-five schedule.

"Shift workers are more commonly men, minorities and individuals with lower educational attainment and typically work in hospital settings, production or shipping industries," noted the study's lead investigator, Dr Marjory Givens, of the University of Wisconsin School of Medicine and Public Health.

The study looked at the health of almost 1,600 employees, 1,400 of whom were also assessed for type 2 diabetes.

It found that shift workers were much more likely to be overweight than those who worked a traditional schedule - almost 48% versus 34%.

Shift workers were also much more likely to have problems with their sleep. Over 23% had insomnia compared to 16% of traditional workers. Some 53% also said they did not get enough sleep compared to 42% of traditional workers, while almost 32% experienced excessive wake-time sleepiness, compared to 24% of traditional workers.

The researchers found that overall, those with sleep problems were more likely to be overweight or obese, and were also more likely to have diabetes. However, this link appeared to be even stronger among people who worked shifts and who did not get enough sleep (at least seven hours per day).

"Shift work employees are particularly vulnerable to experiencing sleep problems as their jobs require them to work night, flex, extended, or rotating shifts.

"This study adds to a growing body of literature calling attention to the metabolic health burden commonly experienced by shift workers and suggests that obtaining sufficient sleep could lessen this burden. More research in this area could inform workplace wellness or healthcare provider interventions on the role of sleep in addressing shift worker health disparities," Dr Givens added.

Details of these findings are published in the journal, Sleep Health.