Written by Dr. Nicole Avena
Dr. Avena is a professor, research neuroscientist, and author on food & addiction. She has done extensive research on sugar and the effects it can have on health. She is the author of Sugarless: A 7 Step Plan to Uncover Hidden Sugars, Curb Your Cravings and Conquer Your Addiction.
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The relationship between sugar intake and sleep is more important than you may realize. Research reveals that high sugar intake can negatively impact sleep quality, while poor sleep can lead to increased cravings for sugary, processed foods. This creates a cycle where both sleep deprivation and excessive sugar consumption feed into each other, affecting your energy levels, mood, and even weight.
Ready to improve your sleep? Learn more about how reducing sugar intake can boost your sleep quality and overall health.
Importance of Sleep
In recent years, scientists and healthcare professionals have collectively realized just how much getting enough sleep can positively impact one’s health. This is because whenever we sleep, our body has the opportunity to conserve energy, recover, restore nutrients, reset from daily activities, and reorganize our brains in various ways to allow for memory consolidation and recharge our cognitive processes.¹ To help these processes work as they are intended to, it is recommended that the average adult should receive 7 to 9 hours of sleep on average.² Although missing one night of adequate sleep may result in not feeling too great the following day, long-term sleep deprivation can be extremely detrimental to overall health. Symptoms of inadequate sleep can include memory impairment, agitation, lack of energy, lack of coordination, a diminished immune system, and even weight gain.¹
The Relationship Between Sugar and Sleep
In addition to excessive sugar intake being linked to increasing our risk for mental health complications, metabolic conditions, weight gain, and more,³ new research has begun to explore how sugar intake and sleep disturbances might be linked.
Current research indicates that sugar and sleep may be codependent, meaning your sleep can impact your sugar intake, and your sugar intake can impact your sleep. Let’s first look at how excessive sugar intake may negatively impact your sleep.
How Added Sugar Affects Sleep Quality and Health
In a study that looked at the impact of added sugar intake in a college population, 72% of participants reported an added sugar intake that exceeded 10% of their total energy intake each day.⁵ College students had reported choosing foods high in added sugar due to lack of time, insufficient knowledge on preparing nutritious foods, cost, and the availability of convenience foods.⁵ In this study, 100% of the participants who had a diet high in sugar had poor quality sleep, while only 65.2% of participants in the low sugar group had poor quality sleep. ⁵ The study found there to be a connection between higher added sugar intake and poor sleep quality, and it also found that sleep enjoyment decreased when caloric intake from added sugars increased.⁵
The study also highlighted the inverse relationship between added sugar consumption and sleep quality. It stated that sleep deprivation is linked to “impaired glucose metabolism and high blood sugar levels,” which are markers for prediabetes. This may help explain the pattern of undesirable food choices and increases in appetite.⁵ Impaired glucose metabolism and high blood sugar levels can disrupt insulin function, leading to increased hunger and cravings for high-carbohydrate, sugary foods. This happens because the body's cells don't get enough glucose for energy, prompting the brain to signal for more food, which can result in poor food choices and overeating. The relationship between sleep and sugar appears to be a vicious cycle both sugar and sleep impacting the other.⁵
Overindulgence and Sleep
According to the Cleveland Clinic, it is best to avoid eating before bed as it goes against your body’s circadian rhythm, which is the natural, internal process that regulates the sleep-wake cycle and repeats roughly every 24 hours, influencing various biological functions such as hormone release, body temperature, and metabolism.⁸ Our bodies are most sensitive to insulin in the morning because circadian rhythms align metabolic processes with daytime activity, and our insulin resistance increases at nighttime to prepare the body for fasting during sleep⁸ .Due to this, overindulging in ultra-processed foods before bed may result in those calories being converted to, and stored as, fat during sleep.⁸ Since eating before bed may impact your circadian rhythm, there is potential that over time, your body may associate night time with day time, as food is typically consumed during the day. This may result in difficulty sleeping at night and negatively impact sleep health.
Additionally, whenever our diet is rich in ultra-processed foods and high in added sugar, some research actually shows that it can impact our deep sleep.⁶ One study looked at 15 men who were healthy and engaged in regular sleeping habits.⁷ One group of men within the study ate a diet that lacked nutrients and was higher in both added sugar and saturated fat. Each group had their brain activity measured during sleep.⁷ Through this study, researchers found that the group of men who consumed higher amounts of ultra-processed foods that were also high in added sugar, had a poorer deep sleep quality due to a decrease in their slow-wave activity when their sleep was measured in the laboratory.⁷
Sleep Deprivation, Weight Gain, and Sugar Cravings
Now let’s explore the flip side: how sleep (or lack thereof) can promote excess sugar intake. Sleep deprivation has metabolic effects that can put you at risk for weight gain.⁴ Interestingly, individuals who sleep an average of less than 7 hours each night have been found to have a higher average BMI and an increased risk of developing obesity than those sleeping 7 hours or greater.⁴ Although more research is necessary to determine exactly how sleep deprivation is linked to obesity, it is important to look at how inadequate sleep might impact sugar intake.
Lack of sleep can result in an increased appetite, which can make sugary snacks and foods more desirable—leading to overconsumption. Whenever a lack of sleep becomes chronic, it can lead to weight gain and obesity due to the lack of specific hormones (ghrelin, leptin, and cortisol) in the body.¹ Ghrelin is our “hunger hormone;” it signals to the brain that our stomach is empty, and it is time to indulge. Leptin is a hormone that influences appetite. Cortisol is our “stress hormone.” In short, lack of adequate sleep at night can stimulate our appetite and result in overconsumption of ultra-processed, high in added sugar foods—which may contribute to obesity when sleep deprivation becomes chronic.
Conclusion
When it comes to added sugar intake, the American Heart Association (AHA) men should consume no more than 9 teaspoons (36 grams or 150 calories) of added sugar per day and women should consume no more than 6 teaspoons (25 grams or 100 calories) per day⁹. Added sugar is desirable and unfortunately extremely hard to avoid with the current food supply in America; however, it is best to limit your intake of added sugar as much as possible—even lower than the recommended amounts if you are able to.
Improving your sleep and reducing sugar intake may seem challenging, but small changes can make a big difference in your overall health. By being mindful of how sugar affects your sleep and how lack of sleep increases cravings, you can break the cycle and move toward a healthier, more energized lifestyle.
References
1. Cleveland Clinic. Here’s What Happens When You Don’t Get Enough Sleep. Health.clevelandclinic.org. https://health.clevelandclinic.org/happens-body-dont-get-enough-sleep. Published May 29, 2024. Accessed August 2024.
2. Ramar K, Malhotra RK, Carden KA, et al. Sleep is essential to health: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2021;17(10):2115-2119. doi:10.5664/jcsm.9476
3. Avena, N. Sugarless: A 7-Step Plan to Uncover Hidden Sugars, Curb Your Cravings, and Conquer Addiction. Union Square & Co. 2023.
4. Cooper CB, Neufeld EV, Dolezal BA, Martin JL. Sleep deprivation and obesity in adults: a brief narrative review. BMJ Open Sport Exerc Med. 2018;4(1):e000392. Published 2018 Oct 4. doi:10.1136/bmjsem-2018-000392
5. Alahmary SA, Alduhaylib SA, Alkawii HA, et al. Relationship Between Added Sugar Intake and Sleep Quality Among University Students: A Cross-sectional Study. Am J Lifestyle Med. 2019;16(1):122-129. Published 2019 Aug 23. doi:10.1177/1559827619870476
6. Harvard Health Publishing. Eating junk food may affect deep sleep. Health.harvard.edu. https://www.health.harvard.edu/staying-healthy/eating-junk-food-may-affect-deep-sleep. Published September 1, 2023. Accessed August 2023.
7. Brandão LEM, Popa A, Cedernaes E, Cedernaes C, Lampola L, Cedernaes J. Exposure to a more unhealthy diet impacts sleep microstructure during normal sleep and recovery sleep: A randomized trial. Obesity (Silver Spring). 2023;31(7):1755-1766. doi:10.1002/oby.23787
8. Cleveland Clinic. Health.clevelandclinic.org. Is Eating Before Bed Bad for You? https://health.clevelandclinic.org/is-eating-before-bed-bad-for-you. Published March 23, 2022. Accessed August 2024.
9. How Much Sugar Is Too Much? | American Heart Association. Published/Updated September 2024. Accessed October 2024.