7 Ways Poor Sleep Leads to Weight Gain

There is a big connection between sleep and fat. Simply put, if you’re staying awake until the wee hours of the morning, your body starts storing fat. But sleep isn’t just about a number of hours. So, if you’re frequently waking up throughout the night, your body is storing more fat. In my blog post, “Sleeplessness is not a badge of honor,” I briefly mentioned how sleep deprivation negatively affects your thought processes and emotions. But unhealthy sleeping habits can also bring unwanted changes to your body … like weight gain. More specifically, it’s fat gain.

When you’re not sleeping well, your metabolism suffers. Below I describe 7 important metabolic changes that take place during sleep deprivation, and the 7 hormones at the center of it all.

Melatonin for Sleep

60 million people in the United States take meds to help them sleep. 60 million! And you might’ve heard of one holistic option - melatonin. So ... melatonin is not really a medication. It’s a naturally derived hormone.

Melatonin comes from the pineal gland in the brain. It is your “get-ready-for-sleep” hormone, and its levels coordinate with your body’s internal clock. The thing is - your internal clock is set for you to be awake while the sun is up and asleep when the sun is down. It surges between 11 PM and 3 AM. Darkness stimulates melatonin. But light blocks it.

Melatonin and Weight Gain

What might be surprising news is that melatonin activates brown fat. Brown fat is special because it burns lots of energy by generating heat. And this leads to body fat loss! Even more surprising - in studies where pineal glands were removed from rats - the rats gained fat! If the rats were then given doses of melatonin, they lost the body fat!

If you’re awake in the middle of the night, even the artificial light of a lamp is inhibiting melatonin. Melatonin is then unable to activate brown fat. The final outcome is increased weight gain.

Insulin and Sugar

Insulin is your sugar storage hormone. It’s released by your pancreas. If you’d like to read more about how it works, check out my blog post “Understanding Your Blood Sugar.” For now, here’s a quick rundown:

when your blood sugar is high, your insulin level will rise. Insulin puts the sugar away and signals your body that there is plenty of sugar to burn. In that way, insulin prevents you from using fat as energy. Your body thinks burning fat is inappropriate because it has plenty of sugar to burn.

Insulin Resistance Causes ...

When blood sugar is high often, more and more insulin is released. Eventually, the insulin is not as intimidating to your blood sugar as it should be. So, it starts to ignore it. Regardless of how much insulin there is, your blood sugar stays high. This is called insulin resistance and insulin resistance causes diabetes.

You may be surprised to know that poor sleep leads to insulin resistance just like high sugar does. That means sleeping poorly can lead to diabetes. In fact, previously healthy young men become insulin-resistant after just a week of sleep deprivation. And their brand new insulin-resistance has nothing to do with appetite or hunger. But it may be linked to the hormones I discuss next.

Cortisol and Stress: the Fight or Flight Response

Cortisol is a stress hormone that comes from your adrenal gland. You might be familiar with it because it helps activate the “fight or flight” response. And this response is intended to keep you safe in dangerous situations. In times of stress, cortisol helps you stay put to “fight” for your life or “flee” (run) for your life.

Cortisol Levels

Your cortisol levels are highest in the morning between the hours of 4 AM and 8 AM. Then, over the course of the day, your levels of cortisol decrease. Cortisol continues to decrease as you get closer to bedtime. The goal is that your energy level will also decrease to get you ready for sleep.

Cortisol Levels and Fat

When you lose sleep, your evening level of cortisol stays up when it should be going down. So, the increased level of cortisol is telling your body to be ready to “fight” or “flee” for your life. Because a life-threatening situation requires immediate energy, cortisol raises your blood sugar. This is because sugar is your body’s first choice for quick energy. As discussed in the section on insulin, high blood sugar shuts down fat burning. So, you gain fat as long as your cortisol levels are high.

Leptin

Leptin is a satiety hormone. It tells your brain your full. Leptin is released mostly from body fat. So, the more body fat you have, the more leptin you have. And yes, the less body fat you have the less leptin you have. And leptin sees fat as energy. So, leptin tells your brain that you’re full because you have enough energy. So, you stop eating. Leptin also stimulates your metabolism - your fat-burning metabolism.

Overnight, while you sleep, leptin’s levels are highest. Leptin tells your brain that your body has enough energy. So, it’s safe to rest.

Leptin and Weight Gain

On the contrary, when you’re not getting adequate sleep, leptin levels are low. Your body thinks you don’t have enough energy and that you need more. So, your body goes into survival mode, storing fat instead of burning it. Your body is thinking, “Danger! Better hold onto this fat ... might need it for fuel.”

When you’re sleeping poorly, you end up more hungry. Your metabolism slows down too. Both changes lead to weight gain.

Ghrelin

Ghrelin is a hunger hormone. It comes primarily from your stomach and tells your brain it’s time to eat. It’s released when your body needs energy. Ghrelin’s levels are highest right before you eat and lowest just after eating.

During sleep, your levels of ghrelin go down. Your body understands that you need less energy while you sleep. So, you need less food or fuel.

But when you’re sleep deprived, ghrelin goes haywire. Ghrelin goes up overnight when it should be down! So, your brain gets the message, “Let’s eat!” More than that, your body stores fat when ghrelin is up.  You won’t burn fat because your brain thinks you have a shortage of energy.

Leptin and Ghrelin

There is a leptin-ghrelin dance. Leptin puts a stop to eating and stimulates your metabolism. Meanwhile, ghrelin tells you to eat and revs up your appetite. But the dance is completely uncoordinated when you’re sleeping poorly. And it leads to weight gain!

Human Growth Hormone

Human Growth Hormone or HGH is notorious as a performance-enhancing drug. But, you make HGH! It’s a totally natural hormone! It’s comes from the pituitary gland in your brain, and it helps burn fat! It also builds, maintains and repairs muscle. Its levels are highest in kids and decrease with age. That’s why it’s also called “the youth hormone.”

Human Growth Hormone and Weight

HGH levels are also highest overnight … ideally, when you’re sleeping. It peaks between 10 PM and 2 AM. So, if you’re awake during typical sleeping hours, growth hormone doesn’t peak. You then have lower than normal levels of HGH. And the lower your HGH is, the more you lose muscle and store fat.

Testosterone

You may be surprised to learn that testosterone is important for women … and men! Testosterone mostly comes from the ovaries. In men, testosterone is released from the testicles. It affects your mood, sex drive and muscle building.

While you’re sleeping, your testosterone levels rise. In fact, the levels are highest during rapid-eye movement (REM) sleep. So, poor sleep is linked to lower testosterone levels. A landmark study showed that young, healthy men who slept for fewer than 5 hours each night had a 10 to 15% drop in their testosterone. This is like aging 10 to 15 years!

Low Testosterone

Low testosterone, in the setting of sleep deprivation, can lead to reduced vitality, libido and muscle. And yes! Low testosterone is associated with increased body fat.

Here’s my take-home message - don’t wait to make sleep a priority. For one, you deserve to look your best. But also, body fat is closely linked to scary stuff like diabetes and heart disease. Most of the hormonal changes I discussed above were active after just one night of short or interrupted sleep. And there were measurable differences in study participants in weeks, not months or years.

If you're ready to make positive changes in your sleeping habits, why not start by setting up your sleeping environment - your bedroom? With a little intention and time, you can transform any space into a sleep sanctuary. Click here to learn a science-backed method, “7 Steps to Set Up Your Sleep Sanctuary.”