It has been clearly documented that sleep deprivation can result in weight gain, so a critical part of any diet is getting enough sleep. A study of 1000 people in the Archives of Internal Medicine, found that, on average, overweight people slept 16 minutes less every night. While this seems like a small difference, think about it over a week, an average overweight person sleeps almost 2 hours less per week than a healthy person. Similarly, a Nurses’ Health Study followed 68,183 women for 16 years (talk about dedication!), they found women who slept less than 5 hours a night were almost a third more likely to gain 30+ pounds than women who slept for at least 7 hours a night.
Another study supports this by finding that when people are only allowed to sleep for 4 hours a night they eat more than when they have had 8 hours of sleep. The University of Colorado found that losing a few hours of sleep for just a few nights in a row caused people to gain an average of two pounds.
But why? Researchers at the University of Chicago believe that sleep deprivation may affect how we regulate appetite, leading to cravings. Perhaps by increasing the amount of food you want to eat, but most likely by changing the type of food you crave. So, when you haven’t slept enough you crave food with fats and carbohydrates more than when you’re well rested. Sleep deprivation will also decrease the amount of exercise you do and lower your metabolism. Essentially, they believe sleep deprivation is a triple threat.
Here’s the exciting part! A new study published in Nature Communications gives evidence for what the researchers at Chicago believe. The study shows that just one night of sleep deprivation changes the way our brains view high-calorie junk food. On days after inadequate sleep, fattening foods and sweets evoke a stronger response in a part of the brain, the amygdala, that controls motivation to eat. Essentially, when you don’t get enough sleep, junk food becomes more enticing to you. Simultaneously, sleep deprived subjects had reduced activity in the frontal cortex, a part of the brain known to play a role in rational decision-making. Meaning, when you don’t get enough sleep, it’s hard to make well-balanced decisions – not exactly news – but definitely something to think about when you’re trying to stick to a strict diet.
So this new study suggests that lack of sleep has a double hit on your waistline, first by increasing your desire to consume fatty foods and second by lowering your ability to avoid giving into the cravings.
How did they determine this? They assigned healthy men and women to two different regimes separated by a week. The first was to sleep for 8 hours and wake up to a small breakfast, then look at 80 pictures of foods and determine how badly they wanted to eat them. The second was to stay up all night and then evaluate the same foods. The sleep-deprived subjects exhibited a strong preference for high calorie foods when compared to the well-rested subjects. The foods the sleep-deprived subjects chose added up to an average of 600 calories more than the rested group.
Brain scans mirrored this desire for high caloric foods by showing increased activity in the amygdala of sleep-deprived subjects when looking at fatty foods. This was accompanied by reduced activity in the frontal lobe indicating reduced decision making ability.
But why does sleep-deprivation result in increased activity in the amygdala and reduced activity in the prefrontal cortex? One theory centers around the accumulation of adenosine. This is a metabolic byproduct that can disrupt neural function and results in feelings of sleepiness when it builds up. Caffeine can block adenosine, which is one of the ways it helps us feel more awake and alert. Sleeping flushes adenosine out of your system and essentially reboots the brain. It’s possible that without sleep, adenosine affects the neural networks in the amygdala and frontal lobe that we have been talking about. Hopefully future research will shed more light on this theory.
Are you getting enough sleep?
Most people need 7 to 8 hours of sleep per night. If you regularly feel sleepy in the afternoon or evening then you’re probably not getting enough sleep at night. The need to nap is a good sign that you’re sleep deprived. If you’re trying to lose weight you should really try to monitor and regulate your sleep.
Another benefit to adequate sleep is that you are more likely to exercise and burn more calories. In turn, the exercise will help you sleep better preventing you from unnecessary food indulgences. Beyond the realm of weight loss, proper sleep has been shown to be beneficial to every single organ in your body. I hope you feel inspired to get good nights sleep!