“We know that marijuana activates the endocannabinoid system and causes people to overeat when they are not hungry, and they normally eat yummy sweet and fatty foods,” Hanlon said. Sleepy brains neglect half the world | Mo Costandi Read more 
 
 When sleepy, the participants had terrible trouble resisting the snacks, even when they were full, said Erin Hanlon, who led the study at the University of Chicago. It was a small but intense study of 14 people in their 20s, who agreed to spend four days at a stretch in the university’s sleep center, where they stayed in rooms where light and sound were controlled. The volunteers’ time in bed was controlled, so that on one visit they averaged 7.5 hours of sleep a night, but on the other only 4 hours 11 minutes a night. She found that when sleep-deprived, volunteers had higher and more persistent levels of endocannabinoid 2-AG, a chemical that ramps up the pleasure felt when eating, especially sweet or salty high-fat foods. And other research has shown sleep deprivation affects the “appetite hormones” ghrelin and leptin, although those effects are not clear-cut. Writing in the journal, Hanlon says this may boost and prolong the pleasure people get from snacking, putting them more at risk of weight gain: “The early afternoon drive for hedonic eating may be stronger and last longer in a state of sleep debt.” 
 
 
 
 In a commentary published alongside the report, Frank Scheer, director of medical chronobiology at Brigham and Women’s Hospital in Boston, says the new findings make for “compelling evidence” that endocannabinoids and food reward mechanisms underpin the excessive eating and weight gain that comes with sleep loss. Obesity and a lack of sleep both raise the odds of heart disease and other health problems and a lack of sleep is clearly linked with obesity. After several nights of poor sleep, healthy volunteers who took part in the study reached for snacks containing more calories - and nearly twice as much fat - than ones they favoured after sleeping well for the same period, the scientists say.
– If you've wondered why you nosh like crazy after a night of tossing and turning, scientists think they've figured it out: Your brain may compensate for the lack of sleep by releasing chemicals similar to those that pot smokers breathe in, resulting in the tired person's version of the "munchies," NBC News reports. In the study published in the journal Sleep, a University of Chicago team led by Dr. Erin Hanlon found that blood levels of an endocannabinoid known as 2-arachidonoylglycerol (aka 2-AG)—a chemical produced in the brain that's similar to those found in pot and that typically appears in the blood at peak levels in the afternoon and stays low overnight—actually kept rising after the afternoon spike and remained high all evening in subjects who were sleep-deprived. Not only did the drowsy participants find it harder to resist nibbling, they chose not-so-healthy snacks. People who use marijuana and overeat also "tend to eat things that are yummy and rewarding," Hanlon says. In this admittedly small study (14 people in their 20s), the subjects camped out for four days at a time at a sleep center, with some volunteers allowed to doze for 8.5 hours a night while others only got 4.5 hours. On the fifth day, the subjects' first meal was delayed until 3pm, followed by unlimited snacks, then a second meal at 7:30pm. All subjects gorged during the first meal, taking in around 2,000 calories each, but the subjects with less shut-eye ate 1,000 more calories during the rest of the day (and mostly salty or sweet junk food); the rested subjects consumed just 600 more calories. Some of the tired subjects had trouble resisting these "reward" foods even when full, per the Guardian. "If you have a Snickers bar, and you've had enough sleep, you can control your natural response," Hanlon tells NBC. "But if you're sleep-deprived, your hedonic drive for certain foods gets stronger, and your ability to resist them may be impaired, so you are more likely to eat it. Do that again and again, and you pack on the pounds." (Here's something else that can have a similar effect.)