Sleep and Diet

Why what we eat and when we eat impacts our sleep patterns, and ultimately, our waistline

By Ashley Little

At some point in your life, you have probably heard one of the following theories:

Rather than speculating whether these theories are true or not, we sought to understand the science behind nutrition and sleep; specifically, how diet can affect sleep quality and, ultimately, weight gain.

Mattress Advisor called on the expertise of Tracy Owens, Registered Dietitian and founder of Triangle Nutrition Therapy, to answer all of our questions about how what we put into our bodies can lead to good (or bad) sleep.

You’ll be excited to hear shedding a few pounds starts in bed.

Why Sleep Deprivation May Expand Your Waistline

“Studies show that people who get less than six hours of sleep are much more likely to gain weight,” Tracy informed us. However, what’s up for debate is whether lack of sleep is the cause or the effect of weight gain.

“It’s kind of both. A vicious cycle, if you will,” she says.

For example, a person who doesn’t get enough sleep lacks energy. Therefore, they might take in a lot of caffeine products. These caffeine products keep them from getting enough sleep (more on that later), and “if you think about it, most caffeine products don’t have many vitamins and minerals. They tend to be sugar-laden,” Tracy points out.

So it could be that unhealthy products consumed to keep you awake are to blame for unwanted weight gain, but there may be a more scientific explanation.

How Lack of Sleep Affects Your Appetite

Did you know that sleep deprivation can actually increase your appetite? To make matters worse, it can cause you to feel insatiable at the same time. Talk about a double whammy.

“Lack of sleep causes hormone disruption. Two of the hormones affected by sleep loss are called leptin and ghrelin,” Tracy tells us.

“Leptin is the hormone that helps you feel full,” she continues. Sleep deprivation causes leptin to decrease. Meaning the less sleep you get, the less satisfied (or full) you feel after a meal. Ghrelin, on the other hand, is known as “the hunger hormone.” Its job is to help you feel hunger. Sleep loss causes ghrelin levels to rise. The fact lack of sleep interrupts the regulation of these hormones simultaneously, is not good news for your waistline.

Whether the cause of weight gain is hormone disruption or increased consumption of sugary caffeine products, the more weight you carry, the more prone you’ll be to sleep disorders, like sleep apnea, that prevents restful sleep. And so the vicious cycle continues.

Sleep and Muscle Regeneration

On the flip side, athletes who strive to gain lean muscle mass also need to pay attention to their sleep, in addition to getting their diet right. Tracy often works with athletes trying to increase muscle mass.

“Athletes do all that work in the gym and [work to] get the right proteins, but if they want to increase lean muscle mass then they have to get enough sleep because that’s where regeneration occurs. If you’re not sleeping enough, then your body won’t have time to grow any muscle because it’s too busy trying to take care of the other important stuff (like white and red blood cell regeneration).”

What and When You Eat Impacts Your Sleep Quality

At some point or another, you’ve probably heard that you shouldn’t eat too close to bedtime. We wanted to see if there was any truth to that statement, so we asked our expert. According to Tracy, the answer is yes and no, for a couple of reasons.

Why Eating Before Bed Could Disrupt Your Sleep

1. Your body is too busy digesting to wind down

“If you eat a large amount of food too close to bedtime, then your body is busy digesting. This makes it harder to rest and get good sleep,” Tracy says.

2. It makes you uncomfortable

“Physically being full can make you uncomfortable, which can also make it hard to get to sleep,” she explains. If you suffer from heartburn or acid reflux, eating too close to bed can trigger these problems. This makes it difficult for you to get comfortable and relax so that you can fall asleep.

While it’s important to be aware of possible discomfort from eating too close to bedtime, there is no hard and fast rule that says you shouldn’t eat after a certain time.

“You body is working 24/7. It doesn’t clock in and clock out when it comes to digesting food. But it is important to be aware of what your body is doing after you eat,” Tracy tells us. If you are hungry before bed, it’s fine to have a snack. Just choose something easy and light or opt for a glass of warm milk.

Common Foods That Impact Sleep

If you want to get adequate sleep, here are a few food and beverages to close to bedtime:


It was no shocker to hear Tracy tell us the main thing to avoid before bed is caffeine. Caffeine is the most common culprit for interrupted sleep when it comes to diet.

Caffeine is a central nervous system (CNS) stimulant that affects everyone differently. In fact, just as you can develop a tolerance to alcohol, you can also become tolerant to caffeine the more you drink it (which is no reason to increase your intake). That’s why a person who doesn’t consume caffeine every day might be wide-eyed and bushy-tailed at 11 pm even if they had a cup of coffee at lunchtime.

However, the effects of caffeine go much further than exposure to the drug. Genetics* can also affect how the body responds (or does not respond) to caffeine intake.

“With DNA testing, we can see people’s gene markers for caffeine. Some people are slow metabolizers of caffeine, meaning it stays in their system longer. Others are fast metabolizers,” Tracy informs us.

Because caffeine causes different reactions in different people, nutritionists can’t give hard and fast advice on consumption parameters. Tracy’s recommendation, regardless of your tolerance, is to avoid drinking caffeine after 3 pm. This is impart because caffeine has a half-life of six hours.

The half-life of caffeine explains how long the drug stays in your body. This means that if you drink 100 mg of caffeine at 3 pm, then at 9 pm (six hours later) 50 mg will still remain in your system. At 3 am (another six hours later) 25 mg will remain, and so on.

If you are having trouble sleeping, you should definitely look into caffeine consumption as a factor.

Caffeine and Genetics

Aside from caffeine consumption, but important nevertheless, is a discovery found in gene testing that pertains to the neurotransmitters glutamate and GABA.

Tracy explains, “The function of the neurotransmitter glutamate, which we have the largest amount of in our brain, is to get us up and going. The other, GABA, is the one that helps us chill, calm down and relax.”

In gene testing, researchers have found that some people have too much glutamate in their brain, which results in difficulty falling asleep and staying asleep.


“All people react to sugar differently. The main thing with sugar is that it doesn’t do us any good at all,” Tracy says.

Sugar is known for causing a spike in energy that’s followed by a crash. That’s because it momentarily boosts blood sugar. Depending on when consumed, sugar can have you wired before bed or ready to flop face down on your pillow.

However, the biggest impact sugar has on sleep is that it increases inflammation, which is the exact opposite of what sleep does — restoration.

Here’s Tracy’s point of view: “[Sugar] is a contributor to inflammation which is the culprit behind all sorts of diseases — autoimmune disorders, arthritis, heart disease, diabetes. Anything that increases that inflammatory process, making us sicker, is not restorative and sleep is all about restoration.”

Sugar is a contributer to inflammation, which is the culprit behind all sorts of diseases. Anything that increases that inflammatory process, making us sicker, is not restorative and sleep is all about restoration.

Something else she points out — many caffeinated products have sugar in them. Talk about a double whammy.


If you have had a glass of wine or a couple of beers recently, you probably noticed that the alcohol made you sleepy. In fact, you may even argue on nights you consumed alcohol it was easier to fall asleep. That’s because alcohol is a depressant that slows the central nervous system. But this is all a facade because alcohol keeps us from getting the deep sleep we need.

“All the research we have on alcohol definitely shows it can make it harder for you to go into a deeper sleep. Although it can make us sleepy, the rest we get isn’t as deep — it’s not REM sleep,” Tracy shares with us.

Fat and Carbs

Fat takes the longest to digest. That’s why Tracy recommends avoiding high-fat, high-carb, greasy foods before bed — they often make you the most uncomfortable and take longer to break down.

Spicy Foods

Although not true for everyone, spicy foods may cause sensations of burning. If that’s the case, you may want to avoid these foods before bed so you can get comfortable.

Aside from foods that can keep you up at night, there are also foods that can decrease your energy levels throughout the day.

Iron Deficiency and Tiredness

“Being iron deficient will make you feel exhausted,” Tracy says. Iron deficiency is more common in women due to the monthly menstrual cycle, but it still occurs in men.

Iron is a component of hemoglobin (which is found in red blood cells) that’s responsible for delivering oxygen from the lungs to other parts of the body. A lack of iron limits the body’s ability to make the red blood cells needed to carry that oxygen. Oxygen gives you energy. When your body doesn’t get the oxygen it needs, you become fatigued. That’s why individuals with low iron feel of exhausted all the time.

Tracy offers a couple of tips for the iron deficient to combat drops in energy:

Eat Animal Protein

There are two types of iron – heme and non-heme. Heme-iron is the iron found in animal proteins; whereas, non-heme iron is found in plants. “Non-heme iron isn’t as abundant and not absorbed as well as heme iron,” Tracy tells us. “If [you] are willing to eat meat (any source of animal protein), especially red meat, that has more iron in it. Also, this type of iron is absorbed better.”

Take an Iron Supplement (or Eat Non-Heme Iron) with a Source of Vitamin C

Vitamin C increases iron absorption, especially the absorption of non-heme iron, which is found in eggs, veggies, and fruits. An article by SF Gate explains that Vitamin C helps release a higher percentage of iron from non-heme sources, thereby boosting your body’s ability to absorb more iron from these foods than it would otherwise.

When you think Vitamin C, you probably think oranges. But there are more sources of Vitamin C than you might think. Strawberries, Brussel sprouts, mangos, broccoli, bell peppers and kiwis all have Vitamin C than the average orange.

Nutrition Tips

Eat a Well-Rounded Diet

Get in the habit of eating a very well-rounded, diverse diet.

“Don’t get into the habit of eating the same food every night, even if it’s healthy. Expose yourself to all the different types of fruits, vegetables, and proteins because each one is so full of nutrients. One nutrient can do some many important things, so we need to get all of them,” Tracy explains.

Picture it like this: “Our body and nutrients work together like a symphony. When everything is working together in the right order, at the right time, it’s beautiful. But when things start to get out of tune, then the whole thing can go down,” Tracy tells us.

Although nutrients come from a variety of sources, they all work together. When we miss out on even a few, things can get out of whack.

Incorporate a Source of Melatonin to Your Diet

“Melatonin is key,” Tracy says. “It is the hormone whose function is to calm and relax you.”

Although our body produces melatonin, there are certain foods we can eat to increase production of the hormone or are a source of the hormone itself.

Our bodies need calcium, B6 and magnesium to make melatonin. “It’s important to not only eat foods that have melatonin in them directly, but to eat foods that supply our bodies the ingredients needed to make it.”

If you want to consume something that contains it directly, “tart cherry juice has the highest concentration of melatonin out there,” Tracy says. Research shows if you drink 8 oz. in the morning and 8 oz. in the evening, it can greatly improve your sleep. To learn more, Tracy recommends checking out

She comments that while a melatonin supplement can help, it doesn’t work for everyone. It’s much better to get it naturally from the food you eat.

Make Sure to Eat Magnesium

Magnesium’s function is to deactivate adrenaline; thus, calming you. “People with restless leg syndrome are often times magnesium deficient,” Tracy tells us.

Try incorporating a good source of magnesium into your diet. It can be found in the following foods:

  • Green leafy veggies, spinach in particular
  • Fish
  • Nuts
  • Dark chocolate
  • Pumpkin seeds

So for those hoping to make changes to their diet, think beyond how food choices affect you during the day, but how they affect you at night. Consider how food could be contributing to your insomnia.

And for those looking to lose a few pounds, remember it’s not all about the work you put in during the day, but how your body recovers at night. (P.S. Don’t beat yourself up if you miss your 5 am work out. You can have peace of mind knowing a few more ZZZs may help you reach your goal quicker.)

Expert Bio

Tracy Owens MPH, RD, CSSD, LDN, founder of Triangle Nutrition Therapy, is a Registered Dietitian that received her Masters of Public Health in Nutrition from the University of North Carolina at Chapel Hill. She is one of approximately 750 Board Certified Specialists in Sports Dietetics (CSSD). Tracy is passionate about providing personalized nutrition strategies that help prevent, improve and sometimes reverse many common medical conditions, such as high blood pressure, pre-diabetes, diabetes, heart disease and many more. She also loves working with athletes to provide accurate and beneficial sports nutrition strategies so they can compete at their very best.

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