Intermittent Fasting and Sleep

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Having problems getting good sleep? Intermittent fasting could be the answer to improving the quality of your shut eye. In addition, eating in a time-restricted window can have benefits beyond better sleep, such as supporting healthy body weight and even improving overall health. Find out why everyone is talking about intermittent fasting and how it may help you sleep and feel better.

What Is Intermittent Fasting?

Intermittent fasting is a dietary practice that involves alternating periods of fasting and eating. During the fasting period, no or very little food is consumed, while during the eating period, normal meals are eaten. Proponents of intermittent fasting (IF) use it as a tool to promote weight loss and improve metabolic health and longevity.

There are several different ways to go about intermittent fasting, including:

  • 16/8 method: fasting for 16 hours and eating during an 8-hour window
  • 5:2 method: eating normally for five days and restricting calories for two days
  • alternate-day fasting: fasting every other day

The History of Intermittent Fasting

Intermittent fasting may be a new trend, but it has a long history. Fasting has been practiced for centuries, often for religious or spiritual purposes. For example, Muslims observe a month-long fast during Ramadan, and Christians practice Lenten fasting. In ancient Greece and Rome, fasting was also a common practice for health reasons.

In modern times, researchers in the 1940s discovered that calorie restrictions on rodents appeared to extend animal life spans. Since then, numerous studies have been conducted on the potential health benefits of IF, and many people follow intermittent fasting as a weight loss or health management strategy. IF has been embraced by some health experts and nutritionists as a way to improve metabolic health, reduce inflammation, and promote longevity.

How Does Intermittent Fasting Work?

There are several ways in which intermittent fasting can work to improve overall health and a healthy body composition:

  1. Reducing calorie intake: By restricting the time window for eating, intermittent fasting can help reduce overall calorie intake, which can lead to weight loss.
  2. Enhancing hormone function: Fasting can increase levels of human growth hormone (HGH), which can aid in fat-burning and muscle growth. It can also improve insulin sensitivity, which can lower the risk of diabetes and improve overall metabolic health.
  3. Improving cellular repair: During the fasting period, the body undergoes a process called autophagy, which involves breaking down and recycling old or damaged cells. This can help improve cellular repair and reduce the risk of age-related diseases.

Why Is Intermittent Fasting So Popular?

Intermittent fasting has gained popularity in recent years for its reported aid in weight loss and other potential health benefits.

One reason fasting is gaining popularity is that it’s simple and convenient. Intermittent fasting can be more convenient than traditional calorie restriction diets because it does not require strict calorie counting or meal planning. Instead, it focuses on when to eat rather than what to eat, which can be more flexible and less time-consuming. It’s a simple-to-follow plan with a straightforward concept that does not require complicated rules or specialized foods. It is also adaptable to different lifestyles, with different fasting schedules and methods available to suit individual preferences.

Lastly, like many health and diet trends, celebrity endorsements and social media have played a large role in the rising popularity of time-restricted eating. The practice has been promoted by several high-profile celebrities and social media influencers, which has helped to increase its popularity and visibility. Celebrities such as Jennifer Aniston, Halle Berry, Kourtney Kardashian, Hugh Jackman, and others have all publicly touted the benefits of fasting.

Health Benefits of Intermittent Fasting

Time-restricted eating has been shown to have several potential health benefits, including:

Weight Loss

By limiting the time window for eating, intermittent fasting can lead to a reduction in overall calorie intake, which is a key factor in weight loss. During the fasting period, the body burns stored fat for energy. Some studies have suggested that intermittent fasting can increase metabolic rate, which means that the body burns more calories even when at rest. Intermittent fasting may help to regulate appetite by improving the hormones that control hunger and satiety. This can reduce the likelihood of over-consuming during eating periods. A meta-analysis reported that, in an overview of 27 different studies on intermittent fasting, all resulted in weight loss for participants.

Improved Insulin Sensitivity

Intermittent fasting can improve insulin sensitivity, which means that the body is better able to regulate blood sugar levels. This can reduce the risk of insulin resistance and type 2 diabetes. A 2022 study on intermittent fasting and insulin sensitivity suggested ​​IF may improve glucose and lipid metabolism, improve insulin resistance, and help patients achieve “significant” weight loss.

Lowered Inflammation

Intermittent fasting has been shown to reduce levels of inflammation in the body. Inflammation is associated with several chronic diseases, including heart disease, cancer, and neurodegenerative disorders. Researchers believe that fasting reduces inflammation by reducing the number of monocytes—cells that cause inflammation—circulating in the blood.

Improved Markers for Heart Disease

Intermittent fasting has been shown to improve several markers of heart health, including cholesterol levels and blood pressure. Studies have suggested that intermittent fasting can reduce the risk for heart disease by improving body weight, hypertension, dyslipidemia (abnormally high levels of fat or cholesterol in the blood), and diabetes.

Reduced Risk of Various Cancers and Neurodegenerative Diseases

Some studies have suggested that intermittent fasting may help protect against chronic diseases, including cancer, Alzheimer’s disease, Parkinson’s disease, and other neurodegenerative diseases. Studies on animals suggest that intermittent fasting may increase longevity and lifespan, although more research is needed to determine whether this effect is seen in humans.

Intermittent Fasting Side Effects

Intermittent fasting is generally considered safe for healthy individuals, but it may not be appropriate for everyone. Some potential side effects of intermittent fasting may include:


Fasting can sometimes lead to feelings of fatigue, especially during the early stages of starting the practice. Be aware of this possible side effect and plan accordingly; you don’t want to run out of steam in the middle of an important presentation.

Headaches and Migraines

Some people may experience headaches or migraines during the fasting period, especially in the early days of intermittent fasting. Dehydration can make fasting headaches worse, so be sure to drink plenty of water. Caffeine may also help relieve symptoms of a fasting headache or migraine.


Lightheadedness can be a common side effect when you first start fasting. Be sure you’re eating to maintain your blood sugar levels during your eating windows. Try scheduling your fasting time to coordinate with your sleep schedule.


Dehydration can worsen other side effects, such as headaches and lightheadedness. Be sure to stay hydrated with plenty of clear liquids, with a focus on water, to avoid dehydration during intermittent fasting. Avoid excess caffeine consumption, which can worsen dehydration.

Digestive Issues

Changes to your diet can lead to digestive issues, including constipation, nausea, bloating, and diarrhea. To reduce the risk of digestive issues, drink plenty of water and be sure to eat fiber-rich foods such as fruits and vegetables during your eating window.


One serious side effect of time-restricted eating is the possibility of malnutrition or nutrient deficiencies. When you introduce IF to your routine, be sure that the meals you are consuming are nutrient-dense. That means filling your plate with vegetables, fruits, whole grains, and high-quality proteins and avoiding ultra-processed foods. Proper nutrition plays an essential role in your sleep and health, and fasting won’t replace the need to eat healthy foods.

Before you begin any diet program, including intermittent fasting, be sure to talk to your doctor. If you have underlying health conditions or are taking medication, it is recommended to consult with a healthcare professional before starting intermittent fasting. Additionally, it is important to approach intermittent fasting gradually and with a balanced diet during the eating periods to minimize the risk of side effects. Some side effects may be short-lasting and slightly unpleasant. Others, however, could be a sign of a serious medical issue. If you have severe or long-lasting side effects, be sure to consult a medical professional.

Who Should Avoid Intermittent Fasting?

Intermittent fasting is generally considered safe for healthy adults, but it may not be appropriate for everyone. The following individuals should speak with a healthcare professional before starting an intermittent fasting practice:

  1. Individuals with a history of disordered eating: Intermittent fasting may trigger disordered eating patterns, including binge eating and purging, in individuals with a history of eating disorders.
  2. Pregnant or breastfeeding women: Intermittent fasting may not provide sufficient nutrients for the healthy development of a fetus or infant, and it may also affect milk production in breastfeeding women.
  3. Individuals with certain medical conditions: Individuals with medical conditions such as diabetes, low blood pressure, or a history of heart disease should speak with a healthcare professional before starting intermittent fasting, as it may affect blood sugar levels and blood pressure.
  4. Children and adolescents: Intermittent fasting is not recommended for children and adolescents, as they require sufficient nutrients for growth and development.
  5. Underweight individuals: Intermittent fasting may not provide sufficient nutrients for individuals who are already underweight.
  6. Individuals taking certain medications: Some medications, such as those for diabetes and high blood pressure, may be affected by changes in diet and meal timing, so it is important to speak with a healthcare professional before starting an intermittent fasting practice.

Be sure to consult a medical professional before starting an intermittent fasting program if you have any pre-existing medical conditions or are taking prescription medications.

Can Intermittent Fasting Affect Sleep?

Benefits of Intermittent Fasting for Sleep

There is some evidence to suggest that intermittent fasting may help you sleep better. Studies have shown that fasting may help regulate the body’s circadian rhythms, which are the internal processes that regulate sleep and wakefulness. This may be due in part to the fact that fasting can reduce inflammation and oxidative stress in the body, which are both factors that can disrupt sleep.

Intermittent Fasting and Insomnia

Insomnia is difficulty in initiating or maintaining sleep. Time-restricted eating in a window that reduces food intake for two to five hours before bedtime may lower rates of insomnia. Researchers believe intermittent fasting helps with insomnia. Abstaining from consuming fatty and acidic food before bed can help decrease nighttime heartburn and acid reflux, resulting in lower rates of insomnia.

How to Sleep Better While Fasting Intermittently

It is important to note that changes in eating patterns and meal timing can sometimes disrupt sleep, especially if you are consuming large or heavy meals too close to bedtime. To minimize the risk of sleep disruption and to sleep better while fasting, be sure you’re planning your eating windows strategically. Be sure to stop eating within two to five hours before going to bed. Avoid consuming caffeine or alcohol close to bedtime.

In addition, you can avoid fasting-related sleeping disturbances with the following tips:

Stay Hydrated

Drink plenty of water while fasting. Staying hydrated will help you feel full and avoid fasting headaches. However, start to slow down on liquid consumption as you approach bedtime, or you’ll be interrupting that fantastic fasting sleep because of a midnight bathroom break.

Focus on Healthy, Filling Meals before Bed

The best foods to eat for better sleep are healthy, nutrient-dense meals that are low in fat and sugar. If you don’t refuel your system for 12 hours or longer, choose protein and fiber-rich foods full of healthy nutrients to keep your blood sugar stable.

Create the Perfect Sleep Environment

Your bedroom could be the key to better sleep. When you optimize your sleep environment for sleep, you can hack your way to more zzzs. Be sure that your room is cool, dark, and quiet. A comfortable mattress and pillow that properly align your spine and comfortable bedding are key to a good night’s sleep. And be sure electronics stay out of the bedroom; notifications and blue light are known sleep disruptors.

Adjust Your Schedule Gradually and Give it Time

Be gentle with yourself when you start intermittent fasting. Know that you may experience side effects such as dehydration or headaches or that you may feel hungry when you wouldn’t expect to. Treat yourself to some extra sleep and ease into it gradually to reduce the risks of side effects and disruptions. Talk to your healthcare professional before you begin, and remember: all good things take some time. Intermittent fasting can have great benefits, but you won’t achieve them all in a single day.


Do sleeping hours count in intermittent fasting?

One of the easiest ways to succeed when intermittent fasting is to plan your fast period for when you are sleeping. Sleep hours definitely “count” for fasting hours. So eat when you’re awake and fast when you’re asleep, and you’ll take most of the hard work out of fasting.

Do you need less sleep when intermittent fasting?

Some studies suggest that intermittent fasting improves sleep by improving circadian rhythms, improving overall sleep quality, and reducing night wake episodes. If your sleep quality has improved and you are getting more quality sleep, you may find yourself needing less sleep when intermittent fasting.

Melissa Zimmerman

Melissa Zimmerman is a writer with a passion for sleep and wellness. When she's not researching and writing about health and wellness, you can find her reading books and spending time with her son and dogs in her Northern California home. Connect with Melissa at