Article authored by Readout Health with editorial oversight from Chief Medical Officer, Naomi Parrella, M.D.
When you’ve had a great night of sleep, you know it. You have an extra pep in your step, feeling mentally sharp, upbeat, and ready to take on the day. Quality sleep is a must to maintain good health, but over 25% of Americans struggle to get it at one time or another.
Sleep scientists suggest that a connection exists between how the body regulates sleep and how it controls its energy balance – that is, how it handles its energy inflow from food eaten and its energy outflow from the energy that’s expended. Given this, can food possibly affect how well you sleep? Several studies say yes, demonstrating that a diet low in carbohydrates may improve sleep quality in several ways.
Sleep: why does it matter?
Life gets busy, and if you often feel like there aren’t enough hours in the day, you’re certainly not alone. Unfortunately, sleep is usually the first to go when schedules get incredibly hectic. Many think nothing of sacrificing an hour or two past bedtime to decompress in front of the TV or stay up too late to meet an important deadline. More than that, millions struggle with sleep disorders like insomnia and sleep apnea, so getting a refreshing night of sleep becomes extra challenging.
While occasional unforeseen late nights are unavoidable, regularly disrupted sleep can have some real ramifications on health. Sleep is critical for restoring the body and keeping the immune system strong. During sleep, the number of proteins and germ-fighting cells needed to keep the body functioning well is at its peak. Quality sleep may also help you keep from gaining weight. Sleep improves the ability to tell when you’re full and suppresses appetite-boosting hormones. And not surprisingly, people who sleep well enjoy better moods, reporting fewer instances of depression, anxiety, and substance abuse. Poor sleep may also boost your chances of developing metabolic syndrome-related diseases like diabetes, obesity, and cardiovascular disease, as well as insulin resistance and cognitive conditions like dementia and Alzheimer’s disease. Plus, poor sleep can worsen the severity of hyperglycemia for people with diabetes.
Slow-wave sleep and your health
During a night of sleep, your body undergoes continuous cycles of two phases of sleep called rapid eye movement (REM) and non-rapid eye movement (NREM). The NREM phase comprises three stages, N1, N2, and N3. Your body cycles through these phases and stages between four and six times every night, each accompanied by a change in eye movements, muscle tone, and brain wave activity. The N3 stage of sleep is called “deep sleep,” and out of all three NREM stages, N3 is the deepest and most restorative. During deep sleep, the body experiences slow-wave sleep or SWS. If you’ve ever woken up feeling especially refreshed, chances are good you’ve spent some decent time in the SWS stage during the night.
Aside from the obvious perk of feeling energized, recent research shows that adequate time in SWS may benefit your metabolic health. For example, more SWS correlates with improved insulin sensitivity, which may explain why people who get poor sleep also tend to experience a higher body-mass index (BMI), or why those who experience disrupted sleep due to obstructive sleep apnea, a sleep disorder, face a higher risk of insulin resistance. In addition, even people who don’t have obesity can see an impaired insulin metabolism when sleep is fragmented.
SWS also contributes to improved cognitive health. Because it influences how the brain consolidates memories, not getting enough SWS is associated with the cognitive decline many experience with aging and conditions like Alzheimer’s and Parkinson’s disease. This decline is thought to occur because during the night, SWS works to clear the brain of reactive oxygen species, highly reactive, unstable chemicals that can damage cells and DNA when in abundance. This toxin and waste removal are believed to be critical contributors to why sleep is so restorative.
Ketone bodies may improve sleep
Recent research discovered that how you eat, namely how many carbs you eat, can influence your sleep quality. When you start limiting your carbs, you’re also limiting the amount of glucose available for your body to use up as energy. Once the body senses that there isn’t enough glucose to run on, it signals the liver to break down fatty acids to produce ketone bodies or ketones. Ketones are then released into the blood to be carried to various tissues to be used for energy. Eating in a way that produces a high amount of ketones promotes sleep quality by enhancing how much SWS you get and helping to synchronize your circadian rhythm. This is because many of the same biological pathways or interactions among molecules in a cell that lead to a change in the cell that are activated during ketone production are also responsible for influencing the body’s sleep-wake cycle, circadian rhythms, and sleep stages. For this reason, it is believed that the presence of ketones with a low carb diet and an improvement in slow-wave sleep go hand in hand, as they are both shown to enhance metabolic and cognitive health.
Along with beneficial ketone bodies, low carb diets also activate orexin neurons, multi-tasking neurons that help handle a variety of critical functions, like feeding, the dissipation of bodily energy via heat production, and the regulation of the sleep/wakefulness cycle. It’s believed that the crucial role of orexins is to control the feeling of wakefulness during the day. To keep a person awake, orexin neurons stimulate other neurons to release chemical substances, like dopamine, norepinephrine, and serotonin, that promote alertness. When the body is short of orexins, excessive daytime sleepiness and sleep conditions like narcolepsy can develop. Researchers theorize that how the body consumes and generates energy can influence how much and how deeply you sleep. When the body stores energy, sleep is intensified, and when energy is generated by stored fat, wakefulness is enhanced. Since fat is oxidized for energy when ketones are produced, it is believed that a low carb diet can result in more activated orexin cells and an alert brain and body.
What the research shows about ketone production and sleep
The ability of low-carb-derived ketone production and orexin to promote wakefulness was confirmed firsthand in a 2018 study during which food cravings and sleep activities of 20 adults with obesity were evaluated over four months. When the subjects consumed less than 50g of carbs a day, they experienced significantly less daytime sleepiness and reported enhanced quality of life.
Eating fewer carbs has also been shown to improve sleep for people with diabetes, according to a 2019 study that tracked the sleep outcomes of 262 adults with type 2 diabetes with a BMI greater than 25 kg/m2 and 116 adults with prediabetes and a BMI greater than 30 kg/m2. The subjects were placed in two groups, with the first group following a low carb diet of less than 30g of carbs per day and the second group making no dietary changes, maintaining their usual care. After one year, the people who ate low carb reported better sleep across the board, specifically enhanced sleep quality, fewer sleep disturbances, and improved functioning during the daytime. Not only did their sleep improve, but the subjects’ severity of diabetes symptoms also improved. In addition, they achieved greater glycemic control and lost weight more effectively. The authors explain that a steady production of ketones through fat intake and carb restriction causes a release of a hormone that promotes satiety or a feeling of fullness.A Japanese study further confirmed the relationship between low carb consumption and better sleep. Researchers analyzed the eating and sleep patterns of 3,129 adult women and determined that the women who ate the fewest low carb sources of vegetables and fish and the most high carb foods like noodles and sweets reported the lowest quality sleep even after adjusting for factors like physical activity, BMI, depression score, and alcohol intake. Also, those who consumed the most sugar-sweetened beverages suffered worse sleep.