Wellness Mind & Body Does Eating Sugar Late at Night Cause Nightmares? Eating sugar and other foods change the chemistry of your brain and body. Learn how that can affect your sleep and dreams. By Kathleen Li Updated on January 31, 2023 Medically reviewed by Jonathan Purtell, MS Medically reviewed by Jonathan Purtell, MS Jonathan Purtell, MS, RDN, CDN, is a registered dietitian at Lenox Hill Hospital. His primary interests include surgical and neurosurgical intensive care, orthopedic, obese/post-bariatric, and gastrointestinal patients. learn more Share Tweet Pin Email gawrav/Getty Images Each day, many Americans eat too much sugar. This can cause a variety of health problems—from heart disease to diabetes—and it can also make you feel tired. But this isn't the only effect that sugar can have on your body. Sugar, and other foods, can affect your sleep as well. Find out more about sugar and what research says about eating sugar before bed. What Is Sugar? When you think of sugar, you may think of the cane sugar in sweets. However, sugars are actually a type of carbohydrate—a "simple" carbohydrate. This means that sugars are made of one or a few chemical subunits. If the chains of the subunits are longer, these carbs are called "complex." How Is Sugar Digested? When you digest food, your body breaks down carbohydrates into sugar subunits. Then, you transport these subunits from your blood to cells across your body, where the cells can use it for energy. Because simple sugars (like sweeteners) are easier to digest, they raise your blood sugar levels quickly. However, complex carbs (like in grains) raise your blood sugar level at a slower rate. The Glycemic Index (GI) is a measure of how fast sugar subunits can make your blood sugar increase—a sign of how long it takes to digest the carb. Sugar enters the blood quickly, so it has a high GI. Complex carbohydrates, on the other hand, have low GIs because they take more time to break down. Does Eating Sugar Late at Night Cause Nightmares? Some people suspect that foods, including sweets, can cause nightmares. One study showed that almost 20% of people believed that certain foods or late meal times could affect their dreams. These study participants most commonly blamed dairy and sugar for their nightmares, though they also thought spicy food could be linked. Researchers from the study are not certain why specific foods might affect dreams, but they do have some theories. One hypothesis is that the chemicals in some foods cause different kinds of dreams. Alternatively, people may be intolerant or have reactions to some foods. These reactions could affect your sleep quality and, therefore, your dreams. Does Sugar Affect Your Sleep? Scientists are still debating how sugar changes your body, but they agree that sugar does affect your sleep. Eating any form of carbs before you sleep could change how you rest—and disrupted sleep could lead to nightmares. Research shows that both the amount and GI of carbohydrates you eat can affect your sleep. An analysis showed that the number of carbs you eat can change how long you stay in different sleep stages. Meanwhile, the combination of amount and GI carbs can affect: How long it takes to fall asleepHow often you wake up while sleeping It May Help You Fall Asleep The complexity of sugars could affect your sleep because sugar can change the levels of tryptophan in your blood. Tryptophan is a chemical used to make serotonin, a brain chemical that promotes sleep. After eating high-GI foods, your body produces more serotonin, helping you fall asleep. By that logic, a sweet snack before bed should lead to better sleep. It May Make It Difficult To Stay Asleep However, one article found that people who ate high-GI foods had a harder time staying asleep. The authors proposed that high-GI sugars would initially make you produce serotonin and feel sleepy. But later, because of the spike in your blood sugar, your body may overcompensate and lower your blood sugar below the normal levels. You could then produce hormones like adrenaline that wake you up. Can Other Foods Cause Nightmares? Eating too much of certain foods—like foods high in sugar—can make your body uncomfortable. The resulting discomfort at night from late-night meals could disrupt your sleep and cause nightmares. One study found that eating foods with higher GI scores was associated with more inflammation— this shows that the study participants' bodies were irritated by the diet. That chronic (long-term) inflammation can lead to other conditions or change your gut microbiome, affecting your sleep in the future. How Can You Snack and Avoid Nightmares? Though researchers are debating how sugar can affect sleep and nightmares, you can try cutting out nighttime sweets and other forms of carbs. If that works to reduce your nightmares, you can keep avoiding them. Avoid Certain Foods and Drinks Besides reducing sugar, you can make other changes to your late-night snacks, like avoiding foods and drinks known to disrupt sleep like alcohol or caffeine. Also, avoid eating fatty or spicy foods before bed, since those can cause indigestion, leading to fitful rest and possibly nightmares. Have a Small Snack if You Have Low Blood Sugar For people with low blood sugar, also known as hypoglycemia, make sure to eat a bedtime snack to maintain your blood sugar level through the night. Some symptoms of hypoglycemia include: ShakinessSweatingConfusionHungerDifficulty speakingFeeling weak or anxious If you have low blood sugar, try yogurt with granola or a graham cracker with peanut butter; both snacks contain carbs to boost your blood sugar, plus protein to keep it from crashing. A Quick Review Even though researchers are still debating how sugar changes your body, they agree that sugar does have an affect on your sleep. Eating any form of carbs before you sleep could change how you rest—and disrupting your sleep could lead to nightmares. Was this page helpful? Thanks for your feedback! Tell us why! Other Submit Sources Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Centers for Disease Control and Prevention. Get the facts: added sugars. American Heart Association. Carbohydrates. National Library of Medicine. Glycemic index and diabetes. Nielsen T, Powell RA. Dreams of the Rarebit Fiend: food and diet as instigators of bizarre and disturbing dreams. Front Psychol. 2015;6. doi:10.3389/fpsyg.2015.00047 Vlahoyiannis A, Giannaki CD, Sakkas GK, Aphamis G, Andreou E. A systematic review, meta-analysis and meta-regression on the effects of carbohydrates on sleep. 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