Ever wonder why after a restless night of sleep or after only getting 4-5 hours of snooze in, you find yourself reaching for that oversized blueberry muffin while at the Dunkin Donuts? Well, there is a ton of science out there showing that sleep deprivation could be contributing to why you choose those high-calorie, highly palatable foods. Going without the appropriate amount of sleep causes biochemical changes that no amount of willpower is likely to overcome. This tendency starts showing up as an ever increasing waistline; people who only sleep 5 hours per night are 50% more likely to be obese than those who get in 8 hours of sleep.
There are 3 major hormones that can become dysregulated by a lack of z’s.
First and foremost is leptin, which is an appetite regulating hormone. Leptin sends a signal to your brain’s hypothalamus that “I’m full, stop eating.” When we are lacking sleep or our sleep quality is disturbed, leptin becomes dysregulated because leptin levels peak in the middle of the night. Sleep deprivation can affect the way leptin is released which causes our brains to override the other signals that the body may be full.
Next is ghrelin, a hormone that tells your brain “I’m hungry.” Just one night of bad sleep can send ghrelin through the roof, leading you to feel more hungry. With food readily available in Western societies, this disruption of leptin, and the spike of ghrelin, is a recipe for overeating and weight gain.
Finally, there’s insulin, which plays an important role in your weight and appetite. Insulin is a fat storing hormone and responds to carbohydrate intake. Therefore, too much insulin such as during insulin resistance, leads to unnecessary fat storage. This fat typically starts accumulating around your vital organs, i.e. visceral fat, and puts you at a greater risk for type 2 diabetes and heart disease. Guess what happens when we don’t get enough sleep or quality z’s? Your insulin levels spike.
What’s even more fascinating is the work that was done by researchers at UC Berkeley related to sleep deprivation and food desire. Using functional magnetic resonance imaging, researchers scanned the study participants’ brains first after a normal night of sleep and then after a sleepless night. They found that high-level brain regions, including the prefrontal cortex, responsible for complex decision making, were blunted by lack of sleep. Even more significant was the increase in amygdala reactivity to food desirability. The amygdala is one of the most primitive parts of the brain and therefore the sleep deprived participants were in survival mode, where making choices about food take on an urgent quality, like issues necessary to stay alive.
The combination of high-calorie food being more desirable and altered decision making may help explain why people who sleep less tend to be overweight or obese. Sleep deprivation has some clear implications related to weight gain and therefore potential weight loss if we get the right amount of quality hours in. Bottom line: you should be getting in 7-9 hours of quality sleep per night to curb cravings and restore normal hormone function.