It’s 3 a.m. and you’re wide awake for the second, third, or fourth night in a row. You’re foraging around in the kitchen for something sweet or starchy, like ice cream, cookies, pretzels or chips. Come morning, you’ll pass on that green smoothie or veggie omelet and dive into pancakes, bagels, or cereal. Sound familiar? Why do junk food cravings get worse with the less sleep you get? New research may provide an answer.
Our cravings for processed junk have ancient roots. Because the next meal was unpredictable for our hunter-gatherer ancestors, our bodies were designed to crave foods rich in fat and carbohydrates, like tubers, berries, and fish, so that we would be sustained until our next meal came along. However, innovation has far outpaced our brain’s evolution, so we still crave these things despite rich, unhealthy food options being readily available at any hour of the day.
Our appetites are controlled by two hormones: leptin and ghrelin. When we get enough quality sleep, our leptin levels increase and our appetite goes down, allowing us to feel satisfied for longer periods. When we don’t sleep well or enough, the opposite happens. Ghrelin levels spike and with it, our hunger. And while these two hormones explain our appetite, they don’t explain our cravings. If we’re hungry, why not simply scratch that itch with something healthy? Why does it have to be junk food?
New research reveals that our endocannabinoid system may be responsible for these unhealthy cravings. This biological system of lipid (fat-based) neurotransmitters binds to receptors and receptor proteins that flow throughout the central and peripheral nervous systems. Its job is to keep the body in homeostasis (equilibrium), and it helps regulate a variety of bodily functions including pain, memory, mood, appetite, stress, sleep, metabolism, immune function, and reproductive function. Endocannabinoids also bind to the same receptors as THC in marijuana, which triggers the “munchies” in many people.
To see how this affected cravings, scientists infused specific regions of animal brains with endocannabinoids to make them eat, and they consistently chose sucrose over saccharin. This wasn’t because one tasted different; rather, sucrose has more carbohydrates and calories.
It is now believed that the endocannabinoid system is what triggers these junk food cravings, and just as poor sleep wreaks havoc on our leptin and ghrelin levels, it seems to negatively impact our endocannabinoid system as well. In another study, sleep-deprived people not only reported a greater increase in hunger than those who slept well, but they also had trouble managing their cravings for unhealthy snacks.
While researchers have yet to determine why sleep effects our endocannabinoid levels, we do know how to nip those junk food cravings in the bud with a simple, if not always easy-to-achieve, solution: Get more sleep. If sleep consistently eludes you, contact me. I can help.