Many professions can require working at night - train engineers, airplane pilots, nurses, police officers - and working these strange shifts often means workers get erratic sleep and can suffer ill effects. For years, sleep researchers have known that people who don't get enough sleep have specific problems. For example, sleep-deprived people are more prone to errors. Now, some new research finds that getting poor sleep also can affect weight.
Siobhan Banks was studying these types of sleep deprivation issues at the University of Pennsylvania. She worked with a group of about 90 people whose sleep was restricted and compared them to people who got normal sleep.
Banks tested their reaction times and ability to recover from sleep deprivation and also weighed them, before and after the study.
"It seems that everybody pretty much over the whole experimental sleep restriction group gained weight," she says. "The average was at about 1.3 kilos."
But when Banks asked the research subjects about this weight gain, they told her their appetites decreased over the course of the five-day study.
"People seemed anecdotally to be largely uninterested in food," Banks says. "I would often go in and see that people had only half-eaten their meals... we gave them regular meals - breakfast, lunch and dinner - and then we sort of had a buffet of snacks that they could choose from at any time."
Banks didn't measure the caloric intake of these subjects, but even though it appears they ate less, they somehow managed to gain weight. Banks isn't sure how this happened, but she has some ideas.
"People may have shifted a little bit from eating a full meal to grazing and snacking more," Banks says.
She also says some other research indicates that sleep deprivation also can change metabolism, and that can be a problem for shift workers, like police officers and nurses.
"I think it's very important that if, say, you are shift worker, to beware of the fact that your sleep disruption may cause some metabolic change," Banks says.
"We're not exactly sure what that is, but it might set you up for having some difficulty in maintaining weight, or it might make you a little more hungry. Certainly, that's what some of the evidence is."
Banks says her plan is to study this phenomenon in more detail.
She recently presented her findings at the annual meeting of the Associated Professional Sleep Societies.