Looking for a better way to lose weight? Maybe it's time to stop counting calories and start counting sheep. A new study has found a link between poor sleep and the marijuana-like "munchie" cravings that may be causing Americans to pack on the pounds.

The study, published recently in the journal Sleep, was a small but intense experiment that carefully controlled the sleep and diet of 14 20-somethings who agreed to spend several days at the University of Chicago's sleep lab. On some nights, participants were allowed to sleep for 8.5 hours, while on others they were only allowed to snooze for 4.5 hours. Each day, the participants were given a large meal at 3 p.m. and allowed to snack from then until their next meal at 7 p.m.

Researchers found that all of the participants binged at that afternoon meal, consuming roughly 90 percent of their caloric needs at one sitting. But it was the participants who were deprived of sleep who continued to snack right up until their next meal, consuming as many as 1,000 additional calories, primarily from low-nutrient, high-reward foods (i.e. junk food.)

Blood tests revealed that the sleep-deprived participants had higher levels of a chemical called endocannabinoid 2-arachidonoylglycerol (2-AG) in their bloodstream than those who got a full night's sleep. 2-AG is a chemical made in the brain that resembles chemicals found in marijuana. It affects pain, pleasure and appetite and has been linked to the "munchies" that pot smokers report feeling after getting high.

Typically, blood levels of 2-AG bottom out overnight but slowly build throughout the day before peaking in the late afternoon and early evening. For the sleep-deprived volunteers, 2-AG levels rose higher than they did for their well-rested peers and stayed high through the evening. This is the same period in which sleep-restricted participants noted feeling hungrier and having a stronger desire to eat. When given snacks at this time, they ate nearly twice as much fat as when they had slept for eight hours.

According to the Centers for Disease Control and Prevention, about one-third of Americans are sleep deprived, defined as getting less than seven hours of sleep each night. Guess how many Americans are also considered obese? One-third.

Coincidence? Maybe not.

Of course, diet and exercise are critical components for maintaining a healthy weight. But as this research points out, a good night's sleep may play an even bigger role in the weight loss equation than previously thought.

Bottom line: If you're trying to lose weight, get to bed at a reasonable hour. You'll be more likely to resist that late afternoon junk food binge if you're not fighting the sleep-deprivation munchies.