WASHINGTON -- A new paper published in the journal Sleep and partially funded by the Department of Defense makes the case that sleep deprivation can trigger powerful changes in eating habits that are akin to the "marijuana munchies." Researcher Erin Hanlon from the University of Chicago described the effect as enhancing "the guilty pleasures" of sweet, salty, high-fat and other potentially bad-for-you foods.

Hanlon and her colleagues' study was small, involving 14 healthy men and women in their 20s, but extremely controlled. All the participants went in for two four-day tests during which their sleep and food intake were closely monitored. During the first visit, the participants spent 8.5 hours in bed each night, resulting in an average of 7.5 hours of sleep. During the second, they were restricted to 4.5 hours in bed and got an average of 4.2 hours of sleep. At each visit they were given identical meals at 9 a.m., 2 p.m. and 7 p.m.

While testing various aspects of their blood during the study, the scientists found an intriguing change. Limiting sleep appeared to amplify and change the daily rhythm of a chemical signal known as endocannabinoid 2-arachidonoylglycerol or 2-AG. That's part of the body's endocannabinoid system, which is believed to affect appetite as well as motor learning, pain and some cognitive functions and is the same one targeted by the active ingredient in marijuana.

In an interview, Hanlon said that when asked about how they felt about food after normal sleep vs. short sleep, the study subjects reported feeling hungrier when they had had less sleep.

"They had a stronger desire to eat and thought they could eat more," she said.

When the volunteers got a healthy or normal amount of sleep during the first stage of the study, blood levels of the signal tended to be low overnight, slowly rise during the day, and peak about 12:30 p.m. But when they were sleep-deprived in the second part of the study, their levels of 2-AG rose higher, peaking about 2:30 p.m., and remained elevated through the evening.

The corresponding impact on their feelings about food and eating habits was striking. Not only did they report higher scores for hunger and a stronger desire, but also, given access to a buffet full of snacks, such as cookies, chips and candy, they ate nearly twice as much fat as when they had slept for eight hours.

Staying awake longer can lead the body to crave more food to create the additional energy it needs, Hanlon said. However, while people are estimated to only need 17 extra calories per extra hour awake, the body appears to overcompensate by triggering binges.

In the study, participants ate an average of 300 extra calories, which is much more than they need. Most of those extra calories were from carbohydrates and fat.

"What we found is that it's not just about energy homeostasis but also for the reward or pleasurable aspects of hedonistic eating," Hanlon said.

In a commentary accompanying the paper, Frank Scheer of the Medical Chronobiology Program at Harvard University's Brigham and Women's Hospital, said that despite the study's small size and short duration, it provides "compelling" evidence that brains as well as bodies are involved in triggering hunger when sleep is inadequate.

SundayMonday on 03/06/2016