How the Fasting Mimicking Diet Can Help Support Restorative Sleep

Guest Author: Dr. Audrey Wells, Sleep Medicine Physician

Dr. Audrey Wells is a board-certified physician in sleep medicine, pediatrics, and obesity medicine, who specializes in treating sleep apnea and insomnia. She is the founder of Super Sleep MD, an online platform offering education and coaching to help individuals improve their sleep health and daytime energy levels.

Sleep is so much more than just rest— it critically supports our mental clarity, emotional resilience, and physical performance; in short, good quality, restorative sleep is the foundation of day-to-day wellness and enhanced longevity. For many individuals, however, poor sleep and metabolic health challenges go hand in hand and create a vicious cycle.

In my practice as a sleep medicine physician, I work with patients to address the root causes of sleep disorders as a means to improve their ability to achieve consistent, restorative sleep. One nutritional approach I recommend, and that emerging research highlights as a potentially transformative tool for improving both sleep and metabolic health simultaneously, is fasting - particularly solutions like Prolon 5-Day Fasting Mimicking Diet (FMD). Many individuals who practice regular fasting cycles report improved sleep quality, with fewer nighttime awakenings, enhanced energy levels, and more consistent circadian rhythms.

The Connection Between Sleep and Metabolic Health

Metabolic health and sleep are deeply connected, with each influencing the other. Sleep supports vital metabolic functions like glucose regulation, hormone balance, and energy use, and poor sleep reduces insulin sensitivity, raising the risk of type 2 diabetes, and disrupts hunger hormones, leading to overeating and weight gain. Elevated cortisol levels from sleep deprivation promote fat storage and worsen insulin resistance, while even decisions about food choice, timing, and portion size are negatively affected by it.

Conversely, poor metabolic health can impair sleep. For example, obesity, linked to metabolic dysfunction, is the #1 cause of sleep apnea. Additionally, blood sugar imbalances in conditions like diabetes lead to nighttime awakenings, while chronic inflammation and circadian rhythm disruptions, common in metabolic disorders, interfere with sleep cycles.

Therefore, by improving both sleep and metabolic health together, we can take steps to break this cycle; one way to do that is through fasting.

How Fasting Positively Impacts Sleep

Research has shown that over time, prolonged fasting (72 hours or more) can offer profound benefits for sleep health by addressing the root causes of metabolic imbalances, including:

• Weight Management: By reducing fat mass, fasting can alleviate pressure on airways, which can improve conditions like OSA.
• Improved Insulin Sensitivity: Fasting can stabilize blood sugar levels, reducing nighttime glucose fluctuations that often disrupt sleep.
• Inflammation Reduction: Lower inflammation levels lead to better hormonal regulation, fostering a healthier sleep environment.

By improving metabolic health, fasting can create a more balanced internal environment. Prolonged fasting has also been shown to activate cellular repair processes like autophagy, a natural mechanism that clears out damaged cells, and to promote cellular rejuvenation.

FMD: Better Support for Sleep and Metabolic Health

While water-only prolonged fasts have some benefits as mentioned above, long-term food deprivation comes with notable risks like nutritional deficiencies, muscle loss, electrolyte imbalances, dehydration, and low blood pressure– not to mention the challenges of adhering to such a stringent protocol in the first place. This is why I’ve found Prolon’s Fasting Mimicking Diet (FMD) to be a more sustainable and effective approach. It uses five days of scientifically formulated foods that stay under the body’s nutrient sensing pathways to mimic the effects of water-only fasting, while still providing essential nutrients to help maintain nutritional balance.

When used 5-days a month over six consecutive months in populations with type 2 diabetes, FMD has been clinically shown to:

• Reduce insulin resistance by 59%
• Promote an average fat-focused weight loss of 22 lbs, while preserving muscle mass
• Lower A1c levels by 1.4%, a key marker of blood sugar control

By addressing metabolic imbalances such as weight gain, high glucose levels, and poor insulin sensitivity, the FMD may directly benefit sleep as well. As a result, FMD offers an accessible and sustainable way to enhance both metabolic health and restorative sleep, while promoting cellular renewal—all without the challenges of complete food abstinence.

How to Support Sleep During Your Fast

What about during a fast? Some may experience worse sleep during fasting periods, possibly due to factors like elevated cortisol and adrenaline levels, heightened hunger signals from ghrelin (often called “the hunger hormone”), and misaligned fasting windows that can interfere with circadian rhythms and melatonin production. These challenges are typically temporary, however. While it may be harder to fall asleep, or stay asleep for as long as usual, many people find that they still feel energized, partially because fasting boosts orexin-A, a brain chemical that helps you stay alert and energized.

For most, the post-fast benefits that foster a healthier sleep-wake cycle far outweigh any potential sleep disruptions that may occur during the fast. Nevertheless, some helpful tips to support better sleep during your Prolon 5-day FMD include swapping around your fasting day’s food items, saving half of your L-Bar to eat later in the evening to alleviate feelings of hunger right before bed, drinking a large glass of water or tea in the evening to help you feel fuller, and limiting your caffeine intake each day (no more than 140 mg/day, equivalent to one standard cup of black coffee).

Beyond Fasting: Additional Tips for Better Sleep

Fasting may better support sleep when combined with healthy nutrition and good sleep hygiene. To maximize fasting’s benefits for sleep, consider integrating these lifestyle adjustments:

• Establish a Wind-Down Routine: Turn off screens, meditate, or read before bed to signal relaxation.
• Stay Active: Regular exercise supports metabolism and improves circadian rhythm regulation.
• Balance Your Plate: Incorporate magnesium- and tryptophan-rich foods like leafy greens, nuts, and seeds.
• Limit Stimulants: Avoid caffeine and sugar, especially in the afternoon and evening.

Sources:

• Brandhorst, S., et al. (2015). "A periodic diet that mimics fasting promotes multi-system regeneration, enhanced cognitive performance, and healthspan." Cell Metabolism.
• Cahill, G.F. Jr. (2006). "Fuel metabolism in starvation." Annual Review of Nutrition.
• "Fasting Diets and Sleep: An article discusses the impacts of fasting diets on eating behaviors, sleep, mood, and quality of life." Frontiers.
• "Intermittent Fasting and Circadian Rhythms: An article reviews the interactions between intermittent fasting, insufficient sleep, and circadian rhythm disruption on cardiometabolic function." Springer Link. Panda, S. (2016). "Circadian physiology of metabolism." Science. Reutrakul, S., et al. (2018). "Metabolic consequences of sleep disorders." Endocrinology and Metabolism Clinics of North America.
• Sakurai, T. (2007). "The neural circuit of orexin (hypocretin): maintaining sleep and wakefulness." Nature Reviews Neuroscience. Spiegel, K., et al. (2004). "Impact of sleep debt on metabolic and endocrine function." The Lancet. St-Onge, M.P., et al. (2016). "Effects of diet on sleep quality." Advances in Nutrition. Tahara, Y., & Shibata, S. (2013). "Chronobiology and nutrition." Neuroscience.
• "The Role of the Fasting Mimicking Diet (FMD): Wei, M., et al. (2017). 'Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease.'" Science Translational Medicine.