TORONTO, (June 6, 2005) — Here’s something to mull over next time you find yourself groggy and craving a plate of French fries: two recent American studies suggest there’s a direct correlation between sleep deprivation and obesity.

The two studies, both published in the Annals of Internal Medicine, suggest that two hormones regulating appetite — leptin and ghrelin — go seriously out of whack when you’re tired. The University of Chicago study subjected 12 healthy young men to six nights with four hours in bed, followed by six nights with 12 hours in bed. During the six nights with four hours’ sleep, researchers found a decrease in leptin, an appetite suppressant, and an increase in ghrelin, an appetite stimulant.

“The two hormones involved in appetite regulation changed in an order which would predict increased hunger,” says University of Chicago researcher Kristen Knutson. “Plus, the men craved starchy snack foods. Not only did appetite increase, but there was a preference for high-carbohydrate, high-fat foods.”

However, the two studies are small and so far unreplicated, and do nothing but suggest that there are hormone changes related to sleep deprivation. “We know that sleep deprivation results in changes to all sorts of hormones and I think what the studies suggest is that sleep deprivation might also be related to hunger, which in turn, might be related to feeding and putting on weight,” says Dr. Ron Heslegrave, a Toronto doctor specializing in sleep, and who has consulted extensively with the federal government in developing Canada’s proposed Hours of Service regulations.

As for how this relates to truckers, Dr. Heslegrave says that medical researchers simply don’t know enough about truckers and sleep. “We know a significant percentage of truckers have irregular sleep patterns. If they’re given ample time, they can adopt a regular routine for getting from A to B if they’re on a longhaul or LTL route. But generally, the time they’re given and dispatching practices don’t necessarily lead to biocompatible schedules.”

Dr. Heslegrave says there have long been concerns that drivers tend to be overweight, at least after years on the job. He says it’s partly to do with the sedentary nature of driving, but also because of the relatively poor nutritional opportunities available to drivers on the road, all of which will lead to weight gain.

“What these studies don’t tell us is if sleep deprivation has any impact in a chronic way,” he says. ” You can throw a lot of things out of balance through sleep deprivation, but does the chronic sleep deprivation [experienced] by some truckers lead to a chronic re-regulating of these [appetite-related] hormones? There’s no research on that. We’ve been much more concerned about the more direct effects of obesity — hypertension, sleep apnea, respiratory problems, high lipids, and cardiovascular disease. We also tend to be more concerned about the more direct effects of sleep deprivation on drivers, like falling asleep behind the wheel and inattention.”

So what’s a driver to do?

Dr. Heslegrave suggests that drivers try to work with their dispatchers to develop biocompatible schedules for themselves, meaning that they should try to get regular routes where they can work out a regular sleep schedule. It doesn’t mean so much if you’re able to get home at night, but if you’re on a longhaul route you should set sleep as a top priority.

“You might run into trouble with sleep deprivation, fragmented sleep, and all those sleep variables, but if you get more sleep, you’re going to be better off,” he says. “We recommend even short naps to increase the amount of sleep you have. Even 15-20 minutes will be of much more benefit than anything else you can do if you’re sleep deprived.”