Two things we've heard over and over is that Americans are getting fatter and they're sleep deprived. The two actually go hand in hand. Numerous studies over the years have proven this link.

For example, sleep deprived people produce 30% more insulin to keep their glucose levels normal. And our hunger hormones, leptin and ghrelin, are altered so that we're stimulated to eat when we lack sleep. Women in a 16-year study faced a 30% greater chance of gaining thirty pounds in that time if they slept five hours or less a day.

Now a new study further convinces us we need to sleep! Our brains make a chemical called endocannabinoid 2-arachidonoylglycerol or 2-AG. It's related to the active chemical in marijuana and has the same ability to cause the munchies.

2-AG is associated with pleasure and appetite and increases when we lack sleep. That stimulates our brain's reward system, and one study showed people who were allowed just four and a half hours of sleep ate an extra thousand calories a day. Plus they chose fatty, rewarding snacks in the evening hours.

The hunger they felt was correlated with the level of 2-AG in their blood. The sleep deprived had a third higher 2-AG than people on full sleep. While the chemical peaked in the afternoon for the people with normal sleep, it remained high well into the evening for the sleep deprived.

So, we could have a new target for therapies to prevent weight gain, although a simple solution would be for people to get enough sleep. Not only would it keep the weight off, we'd all be less irritable and think clearer. And I'd probably be easier to live with!