Did you know that not sleeping enough (less than seven hours per night) can inhibit your weight loss goals? Say what?! Alright, let’s get into the “why”. Sleep deprivation can impact your hormones, your brain, and your ability to fight against those hormone cues that are initiated with lack of proper rest.
Hormones and Sleep
Within just four days of sleep deprivation, your body’s ability to properly respond to insulin signals begins to diminish. When you’re not responsive to insulin, fat cells are far less able to release fatty acids and lipids to produce energy, blood glucose remains higher, and any extra fats and sugars circulating in your blood cause you to pump out even more insulin. Eventually, all this excess insulin causes you to begin storing fat in all the wrong places, including tissues like your liver, leading to problems such as fatty liver and diabetes.
But wait there’s more! Hunger is controlled by two other hormones that respond to sleep cues: leptin and ghrelin. The hormone leptin plays a big role in controlling your appetite, metabolism and calorie burning. Leptin is the chemical that tells your brain when to feel full, when it should start burning calories, and ultimately impacts when it should create energy for your body to use. It triggers a series of messages and responses that starts in the hypothalamus and ends in the thyroid gland. The thyroid gland controls the way your body stores and uses energy.
During sleep, leptin levels increase, telling your brain you have plenty of energy for the time being and there’s no need to trigger the feeling of hunger or the burning of calories. When you don’t get enough sleep, you end up with too little leptin in your body, which, through a series of steps, makes your brain think you don’t have enough energy for your needs. As a result, your brain tells you you’re hungry, even though you don’t actually need food at that time, and it takes steps to store the calories you eat as fat so you’ll have enough energy the next time you need it. The decrease in leptin brought on by sleep deprivation can result in a constant feeling of hunger and a general slow-down of your metabolism.
Ghrelin is basically the exact opposite of leptin: It tells your brain when you need to eat, when it should stop burning calories and when it should store energy as fat. During sleep, levels of ghrelin decrease, because sleep requires far less energy than being awake does. People who don’t sleep enough end up with too much ghrelin in their system, so the body thinks it’s hungry and it needs more calories, and it stops burning those calories because it thinks there’s a shortage.
Some scientists hypothesize that these hormonal changes that occur during sleep are the result of an evolutionary process that ended up with humans who could survive the food shortages of winters. If you think about the seasons, winters have long nights and little food, and summers have short nights and an abundance of food. With shorter nights comes less sleep, less leptin and more ghrelin, making the body eat as much as possible and save those calories for the long winter ahead. With winter comes more sleep, meaning more leptin and less ghrelin, both of which tell the body it’s time to burn those calories it stored during the summer.
Then there’s the hormone cortisol. When you don’t sleep enough, your cortisol levels rise. Not only does cortisol upregulate food reward centers in your brain that make you want to eat more food, but cortisol can also inhibit the breakdown of fat for energy and increase breakdown of muscle.
The Mind Body connection
As if all these hormonal issues from lack of sleep weren’t enough, it’s also been shown in research that lack of sleep causes your brain to be less resistant to the temptation of junk foods, excess calorie intake, and foods you know you shouldn’t eat. A single night of sleep deprivation is enough to impair activity in a section of your frontal lobe that controls food-related decision making,. When sleep deprived, you also have increased activity in the amygdala, a reward region of your brain that can make you crave high-calorie or very fatty and salty foods and a lot of it, which is one reason why it’s so much easier to give into those tempting comfort foods like the leftover kids’ mac n’ cheese, goldfish, pizza, french fries, etc. When you get enough sleep, you can often fight off these desires, but another area of your brain—a section called your “insular cortex” gets desensitized due to sleep deprivation, and this means you have more trouble fighting the urges to eat highly rewarding foods. Long story short, when sleep deprived, you end up having brain fog when it comes to making proper food choices.
So now what
If you find that you are not getting enough sleep, take steps to retune your circadian rhythm. The most important way to ensure you get enough sleep is to stick to a sleep schedule and create a nightly routine to help cue your mind to start winding down (i.e. brushing teeth, etc). Studies show that going to bed around 9:30/10pm is the optimal time, however you will need to reverse engineer your bedtime based on when you need to wake up. The optimal time for you will be 7-9 hours before you need to get up for the next day. In order to make sure your body stays tuned in to that rhythm, you will want to try to wake up around the same time on the weekends as well (sorry).
The second most impactful bio hack is to go outside and get as much natural sunlight earlier in the day as possible. This can be hard to do if you sit at a desk all day, but there are still small changes you can make that can have a large impact. For instance, set an alarm/reminder once and hour to get up from your desk and take a quick loop around the building. Killing two birds with one stone here since we all know “sitting is the new smoking”. Take advantage of your lunch time by eating for the first 20 min (mindfully), and then using the remainder of your time to go for a walk outside. The more sunlight earlier in the day the better. If you really can’t get outside, try to at least open the blinds and make your surroundings as bright as possible to help signal to your body that it is time to be awake and alert.
Limit your “blue light” at night. Blue light is the light emitted from laptops, tablets, cell phones, etc. Try to limit or eliminate exposure to blue light within 2-3 hours of going to bed. Blue light disrupts your body’s ability to start preparing for sleep. Same goes for exercise, try not to exercise within 3 hours of bedtime.
Along with limiting your blue light, try to avoid snacking 2-3 hours prior to going to bed. If your goal is to be in bed by 9:30pm, that means finishing up your dinner by 6:30/7pm and giving up the late-night snacking. If your body is working to digest food, it will disrupt and take away from the normal restorative processes that occur during sleep. For example, as you sleep your growth hormones naturally rise which burns fat and aids in muscle recovery. If your body is still digesting food, this process gets interrupted and minimizes those “Gainz”. And nobody wants that! Along the same lines, it is best to avoid alcohol for 2-3 hours before bedtime for similar reasons.
Avoid consuming caffeine later in the day, as it impacts and/or reduces your body’s ability to secrete melatonin (the hormone responsible for synchronization of sleep), which in turn inhibits sleep. ( https://www.ncbi.nlm.nih.gov/pubmed/14592218) Ideally, no caffeine consumption after 2pm.
Ok, I know I’ve thrown a bunch of terms and concepts at you that may be a bit to absorb. Long story short, sleep is one of the most crucial, but so often overlooked, aspects to being the healthiest version of yourself. Don’t deny yourself those much needed ZZZ’s! Make it happen!
