Sleep Loss Leads to Junk Food Cravings | VitaMedica
junkfood on plate

Sleep Loss Leads to Junk Food Cravings

It seems like on some days more than others, it’s harder to make healthy food choices.  You just can’t help reaching for the pizza, chips, and ice cream, even when healthier options are available. 


But what exactly affects your decision-making on these particular days?  Hunger?  Bad habits?  Possibly, but a new study has a surprising suggestion – it may simply be that you aren’t getting enough sleep.


The study by researchers at the University of California Berkeley and published in the journal Nature Communications finds a link between sleep deprivation and brain function in the regions that control food choices.


Scientists used functional magnetic resonance imaging (fMRI), to scan the brains of 23 healthy young men and women.  The participants were instructed to follow two different sleep regimens, which alternated with about 10 days in between. 


In the first session, study subjects slept a normal number of hours – about eight hours – in the lab.  When they awoke, they were given a breakfast of toast with strawberry jam.


“Getting enough sleep is one factor that can help promote weight control by priming the brain mechanisms that control appropriate food choices.”


In the second session, the subjects did not sleep.  Over the evening, they were given snacks such as Fig Newtons, Goldfish crackers, peanut butter crackers, and apples to compensate for the additional calories burned by remaining awake.  At the end of the session, they, too, were given a breakfast of toast with strawberry jam.


Immediately following each session, the participants were shown 80 pictures of various foods and asked to rate on a scale of one to four how badly they wanted the food item at the moment.  The foods shown were evenly divided across five categories – salty, sweet, starchy, fruit or dairy – and included fruits and vegetables such as carrots, apples, and strawberries, as well as unhealthy donuts, pizza, and burgers.  As an incentive, participants were told that after rating the foods, they would be given one of the foods they craved most. 


During the rating, an imaging machine measured brain activity.  Researchers found that after sleep-deprivation, activity in the brain’s frontal lobe, the high-level region of the brain that controls complex decision-making, was impaired.  Instead, activity was highly increased in the amygdala, the more “primitive” center area of the brain that controls basic emotions and desire. 


Correspondingly, the sleep-deprived participants favored unhealthy snacks and junk food such as potato chips, chocolate, and sweets.  The more tired they felt, the more they craved these unhealthy foods.


By contrast, the participants who enjoyed a full night’s rest craved unhealthy foods less, amounting to a difference of nearly 600 calories when compared to their cravings after being sleep-deprived.


“This combination of altered brain activity and decision-making may help explain why people who sleep less also tend to be overweight or obese,” wrote Matthew Walker, professor of psychology and neuroscience at UC Berkeley and senior author of the study.


The findings also show that getting enough sleep is one factor that can help promote weight control by priming the brain mechanisms that control appropriate food choices.  It is “the single most effective thing people can do every day to reset their brain and body health,” says Walker.


The Bottom Line

We often hear that people who are sleep deprived are more likely to be overweight.  Other studies have shown that sleep deprivation undermines weight loss, increases appetite, and causes cravings for starchy, sweet, and salty foods, but this study helps us understand how these effects originate in the brain so that we can work against them to lose weight.


An integral part of leading a healthy lifestyle is to get a good night’s sleep.  If you’re not getting a good night’s sleep, here are some ideas on what you can do to promote a restful evening:

  • Exercise, but not too late at night
  • Don’t eat a huge meal just prior to bedtime
  • Stop consuming caffeine after 2:00 P.M., especially if you’re sensitive to its effects
  • Limit or reduce alcohol intake
  • Keep pets out of the bedroom if they disturb your sleep
  • Don’t watch TV in bed – studies show that you’ll keep watching until the show is over, and you won’t turn it off when you’re tired
  • If you’re traveling through time zones, consider taking melatonin to reset your inner clock

Remember, being healthy and being at a healthy weight are part of a holistic approach to wellness.  This includes healthy food choices, exercise, and proper rest.  Don’t just think about wellness when you wake up – make sure you think about it before bed so you can get all the sleep you need!


David H. Rahm, M.D. is the founder and medical director of The Wellness Center, a medical clinic located in Long Beach, CA. Dr. Rahm is also president and medical director of VitaMedica. Dr. Rahm is one of a select group of conventional medical doctors who have education and expertise in functional medicine and nutritional science. Over the past 20 years, Dr. Rahm has published articles in the plastic surgery literature and educated physicians about the importance of good peri-operative nutrition.