HYANNIS – “Sweet dreams” is another way of saying “good night,” but if you don’t get enough sleep, you can end up taking the advice literally.
A recent study showed that people who were sleep-deprived weren’t just extra hungry; they were hungry for junk food. The effect of sleeplessness was similar to the “munchies” experienced by many people when they smoke marijuana – and that’s a recipe for gaining weight.
“The human body works in a unique rhythm, and lack of sleep can throw off that rhythm,” said Mir F. Shuttari, MD, a Falmouth pulmonologist who is certified by the American Board of Sleep Medicine.
Dr. Shuttari was commenting on a study conducted at the University of Chicago in which the hunger and eating habits of healthy young people were tracked when they slept a full night (about 7.5 hours) and when their sleep was cut short (about 4.2 hours).
Those who were sleep-deprived craved cookies, candy and chips as soon as two hours after eating a full, healthy meal.
It’s All About Hormones
“The effects of sleep loss on appetite were most powerful in the late afternoon and early evening, times when snacking has been linked to weight gain,” according to a University of Chicago news release about the study.
“We found that sleep restriction boosts a signal that may increase the hedonic aspect of food intake, the pleasure and satisfaction gained from eating,” said the study’s lead author Erin Hanlon, PhD, in the news release. “Sleep restriction seems to augment the endocannabinoid system, the same system targeted by the active ingredient in marijuana, to enhance the desire for food intake.”
Sleep and awakening have a very close relationship with different hormonal functions in the body, explained Dr. Shuttari.
“In the daytime, you get hungry three times a day – or at least you typically eat three times a day. At night, when you are asleep, generally you don’t have the need to eat through the night. That is because the hormone that makes you hungry is also shut down once you go to sleep.”
When you fall asleep, a hormone called leptin is circulating in your body, he said. Leptin gives you the sensation that your stomach is full and you don’t need to eat. When you’re awake, the opposite hormone, for daytime functioning, ghrelin, circulates and makes you feel hungry.
“When the appetite hormones are unbalanced, you have a tendency to go toward the refrigerator and grab a soda or cookies or candy,” said Dr. Shuttari.
The Extra Activity Does Not Offset the Calories
The University of Chicago study looked at levels of leptin and ghrelin, as well as a chemical signal known as endocannabinoid 2-arachidonoylglycerol (2-AG).
Usually 2-AG is at low levels at night and rises during the day, hitting a peak in the early afternoon. But, for the sleep-deprived study subjects, levels of 2-AG rose an extra 33 percent and stayed high until 9 p.m. The result: when they had a chance to snack, they ate nearly twice as much fat as the rested group.
“The energy costs of staying awake a few extra hours seem to be modest,” said Hanlon. “One study has reported that each added hour of wakefulness uses about 17 extra calories. That adds up to about 70 calories for the four hours 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.”
The findings were published in the journal SLEEP, a joint publication of the Sleep Research Society and the American Academy of Sleep Medicine.
“If you have a Snickers bar, and you’ve had enough sleep, you can control your natural response” and avoid the temptation, Hanlon said. “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.”
While it may be hard with the holiday busyness, Dr. Shuttari recommends that adults aim to get a consistent seven to eight hours of sleep per night for the best health benefits. According to a survey conducted by the Centers for Disease Control and Prevention, about a third of Americans regularly get less than seven hours.