Daydreaming about cheeseburgers, cookies and pizza after a sleepless night?
Scientists have already established a link between craving junk food after losing out on a good night of rest, but in a new study, they explain why we tend to overeat and make poor food choices while sleepy-eyed.
Doctors out of the University of Chicago say lack of sleep amplifies a chemical signal that makes us drawn to sweet, salty and high-fat food. The chemical signals at play are similar to how marijuana triggers its users to binge eat on junk food, they suggest.
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“We found that sleep restriction boosts a signal that may increase the hedonic aspect of food intake, the pleasure and satisfaction gained from eating,” according to Dr. Erin Hanlon, a research associate in metabolism and diabetes.
“If you have a Snickers bar, and you’ve had enough sleep, you can control your natural response. 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,” Hanlon said.
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Hanlon and her team worked with 14 young, healthy volunteers for their research. They spent four days in the research centre where scientists controlled how much sleep they got along with their daily meals.
After a rough night where they only got about four hours of sleep compared to a full seven or eight, they couldn’t turn away from cookies, candy and chips even though they were fed a meal that supplied them with 90 per cent of their daily caloric needs two hours before.
The effects were strongest in the late afternoon and the early evening – when snacking has been tied to weight gain.
The chemical signal is called the endocannabinoid 2-arachidonoylglycerol, or 2-AG, for short. Blood levels of 2-AG are typically low overnight and slowly rise throughout the day, peaking by the early afternoon around lunchtime.
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But when the volunteers were sleepy-eyed, their levels rose higher and stayed elevated throughout the day, even past the 12:30 p.m. mark. They reported higher scores for hunger pangs and wanting to eat, especially at the 2 p.m. mark and again at about 9 p.m.
And when food was placed in front of them, they ate nearly twice as much fat compared to when they slept for eight hours.
Hanlon says one study pegs the extra eating at about 17 calories for each hour of lost sleep.
“But given the opportunity, the subjects in this study more than made up for it by bingeing on snacks, taking in more than 300 extra calories. Over time, that can cause significant weight gain,” Hanlon said.
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Dr. Colleen Carney, a Ryerson University professor and sleep specialist, says that sleep is just as valuable as a healthy diet, drinking less and exercising more.
It’s a bit of a vicious cycle – sleep regulates our appetites because it balances out hormones.
If you aren’t sleeping well, your metabolism takes a hit, along with your eating routine. You could be encountering more cravings or even a loss of appetite.
“What happens is the hormones stimulating appetite are higher, your satiety is lower and your regulation of feeding messes up. People crave saltier food and higher carbs. We see that in what food you pick when you want to snack,” Carney says.
Read Hanlon’s full findings in the journal Sleep.