What happens when you stop eating 3 hours before bed

If you feel like no dinner is complete without dessert, or you find yourself raiding your fridge or snack cabinet a few minutes before crawling into bed, you’re in good company. But unfortunately … it might not be the best habit.

“Activities such as eating and exercise stimulate our body and impact sleep quality and ability to fall asleep,” says Sandra Zhang, a registered dietitian nutritionist at the Frances Stern Nutrition Center at Tufts Medical Center. “It roughly takes about three hours for our stomach to empty its contents.”

Let’s back up for a second: This means that if you go to bed around 10, you would have to close the kitchen up by 7 p.m. If skipping your after-dinner ice cream cone or piece of toast sounds like a terrible idea, remember that sleep is one of the body’s most essential processes, and it can be disrupted when you eat too close to lying down (and especially sleeping).

When you eat late at night, your body has to split its energy between digestion and the natural wind-down process that prepares you for sleep. Blood flow is redirected to the stomach and intestines, body temperature can rise, and hormones involved in digestion are activated — all of which send “wake up” signals to your brain. This can make it harder to fall asleep and stay asleep, even if you don’t notice it happening.

Late-night eating can also increase the likelihood of acid reflux, bloating and discomfort once you lie down, which may cause micro-awakenings throughout the night. Over time, consistently eating close to bedtime may contribute to poorer sleep quality, less time spent in deep restorative sleep, and grogginess the next day. While the occasional bedtime snack isn’t a big deal, making it a nightly habit can interfere with your body’s natural circadian rhythm and recovery processes.

We chatted with registered dietitians to learn about what happens to your body when you stop eating three hours before bed, and how it can affect your sleep and the various systems within your body. Here’s everything you need to know.

Time to wind down

Your body experiences a shift within the few hours of the time you usually go to sleep as it prepares to wind down.

“Before bedtime, our body winds down and transitions to a parasympathetic response that signals relaxation,” Zhang explains.

If you continue consuming food too close to bedtime, Tracey Brigman, a registered dietitian and clinical associate professor at the University of Georgia, and Laura O’Connor, a registered dietitian at NYU Grossman Long Island School of Medicine, note that you run the risk of experiencing increased bouts of acid reflux or heartburn and potentially experiencing sleep disruptions.

Essentially, this three-hour window provides your body with ample time to digest your food, so it can focus on helping you achieve the rest you need instead of carrying out digestive processes during the time you’re supposed to be sleeping.

If you do need to eat less than three hours before bedtime, our experts recommend keeping your options light and low in fat. After all, you don’t want your body to keep you up all night and/or have a disrupted night’s sleep because you’re hungry.

Essential bodily processes

Many systems in your body undergo essential processes after you stop consuming food three hours before bed, all of which are important to keep in mind as you plan your last meal (or snack) of the day.

Your body releases less insulin as blood sugar stabilizes: Given that the body releases insulin to combat the rise of blood sugar in the minutes after eating, the three-hour period is critical for stabilizing blood sugar levels. “During these three hours, our blood sugar stabilizes and less insulin is released over time,” Zhang says.

Your natural melatonin increases: When you stop eating three hours before bed, you’ll probably notice that your body will start to feel ready for sleep, which is not a coincidence. “Ensuring you stop eating three hours before bed helps increase the natural melatonin that induces sleep,” O’Connor says. “If you eat close to bedtime, melatonin production starts later, causing delayed sleeping.”

Your body can focus on sleep: Perhaps one of the most notable effects that often occurs when you stop eating three hours before bed is improved or enhanced sleep quality.

In other words, your body can “keep its natural circadian rhythm,” Brigman says. “Since our body enters the resting phase, we can fall asleep faster, wake up fewer times and enjoy more deep sleep,” Zhang adds.

Since your body is less likely to release cortisol, aka the “stress hormone” (which can be triggered by eating), after three hours, Zhang notes that one is less likely to be stressed, which helps their circadian rhythm adhere to its normal cycle.

Furthermore, “when digestion is mostly complete, core body temperature can drop naturally in the evening, a key signal the brain uses to initiate sleep,” adds Mariana Dineen, a registered dietitian and the founder of Elemento Health.

Your body works to burn stored fat: Since your body will have probably been able to completely digest your last few bites within the three hours, “your body will burn more stored fat instead of digesting the food in the stomach,” O’Connor says.

Your muscles can repair themselves more efficiently: Muscle repair is one of the key processes that can occur when your body can truly focus on resting instead of digesting throughout the night (hence why not eating three hours before bed is important). While you don’t want to eat too much ahead of those three golden hours, you want to ensure you’re getting enough protein to promote muscle repair. “If you are too hungry, your body may use protein for energy instead of muscle repair,” Brigman says.