How Do Sleeping and Eating Work Together?

Medically reviewed by Linda Said, MS, RD, LDN
2020-06-01

Have you ever given in to your food cravings at night or eaten a big dinner right before you go to sleep? 

It could be that our night time eating is not really a result of feeling hungry-- but rather the fear of hunger or anticipation of hunger in the middle of the night - which may trigger that late visit to the kitchen.  

Many people don’t realize that what is eaten at night can affect sleep. Sleeping revolves around rebuilding cells, muscle growth, tissue repair, hormone synthesis…but not digestion! 

Basically, sleeping and eating are not compatible. Here are ways that is true:

Acid Reflux

Upon eating, the digestive system produces acid as a mechanism to help break down food. What typically happens after lying down is that the food starts coming back up and interferes with the digestive process, causing acid reflux or heartburn. 

According to the National Sleep Foundation, acid reflux is "one of the leading causes of disturbed sleep among people between the ages of 45 and 64.” Foods that are associated with acid reflux include: acidic/citrus fruits, spicy food, chocolate, caffeine, alcohol, tomato based foods (sauces, chili), high fat food (fried food, bacon, sausage), carbonated beverages and peppermint.  

Insulin and Melatonin

Insulin is a hormone that is released after eating a meal (triggered mainly by carbohydrates) and helps lower blood sugar. Melatonin (a.k.a.  sleep hormone) is produced deep within the center of the brain, and regulates the sleep-wake cycle. There has been ongoing research that has been looking at the relationship between these 2 hormones, and how this regulates our sleep.  

Melatonin appears to play a role in blocking insulin secretion during the night (meaning, insulin won’t be able to lower blood sugar as much as it should). So eating a late meal will lead to higher than normal blood sugar levels. Having this regular exposure to high blood sugars can increase the risk of developing diabetes and other metabolic disorders. 

So, the key is to try and eat when the metabolism is optimal (i.e. during the day). It’s not only about what to eat, but also when to eat! 

Lack of Sleep and Weight Loss

There seem to be several factors that impact weight loss in the context of sleep deprivation. Sleep time and sleep efficiency are important determinants of metabolism. When people don’t sleep enough or don’t sleep well (as can happen with obstructive sleep apnea, a disorder where people stop breathing during sleep), this leads to suboptimal food storage in the body. This means the body is more likely to store foods as fat. 

Also, sleep debt has been shown to produce high insulin levels, which makes it harder to use existing fat stores. 

To add to that, you’re more likely to make poor food choices when you’re over-tired versus well-rested. 

And if all that isn’t enough, there is one more piece. Lack of sleep also reduces the drive to exercise. 

All these weight loss inhibiting factors have something in common: lack of sleep. 

Alcohol and Caffeine with Sleep

Many seem to fall asleep after 1-2 alcoholic drinks due to alcohol’s sedative effect. But let’s be clear: sedation is not sleep. 

It has been demonstrated that alcohol can reduce REM (deep) sleep which gets replaced with light sleep. Alcohol also “fragments" sleep, causing wakefulness throughout the night and reduces continuous sleep.  

In contrast, caffeine is a stimulant which makes it harder to fall asleep. This is because caffeine can block the sleepiness signal (adenosine) in the brain. 

Sleep expert, Dr. Matthew Walker, recommends cutting caffeine off around midday due to its duration of action. Caffeine has a "half-life of about 6 or 7 hours. And a half-life simply means the amount of time it takes for 50% of the drug to still be in your system or 50% of it to be cleared. Caffeine has a quarter life of about 12 hours. In other words, if you have a cup of coffee at noon, a quarter of that caffeine is still circulating in your brain at midnight.”  

The Bottom Line

Like any behavior, sleeping requires attention and making the time to prioritize it - similar to how you (should) prioritize working out and eating healthfully. If sleeping is a problem, food quality and timing of meals could be an underlying issue. 

It is clear that poor sleep can affect food choices and food choices can affect sleep. This highlights the importance of food quality and finishing the last meal of the day at least 3 hours before bed. This better aligns with when the body is sending a signal to shut down and get ready for sleep.

To get help on how to manage this in your life, get a personalized integrative sleep program that incorporates nutrition, supplements, exercise, and mind-body balance:

Learn more about sleep by understanding insomnia causes and the best treatment options for chronic insomnia