Shiftworkers getting too little sleep at the wrong time of day may be putting themselves at greater risk of diabetes and obesity.
Findings published in the Science Translational Medicine journal show the body struggles to control sugar levels if normal sleep patterns are changed.
A research team at Brigham and Women's Hospital in Boston, Massachusetts, controlled the lives of 21 people including their meal and bed times.
After being allowed 10 hours sleep the participants were then subjected to three weeks of disruptive sleep.
Some developed early symptoms of diabetes.