How Does Fasting Impact Sleep?

How Does Fasting Impact Sleep?
Cordelia Tan

Cordelia Tan | Author

Cordelia Tan, is a passionate advocate for women's health and well-being. Known as Fasty's number one fan, she expertly blends Eastern and Western health practices, offering a holistic approach to diet and wellness. Her work focuses on empowering women with knowledge and practical strategies for a healthier life.

Are you considering starting a fasting regimen but don’t know how fasting may affect your sleep? Conversely, you are already fasting and suspect fasting could be the culprit of your dark circles. 

Adequate sleep is fundamental for optimal well-being, supporting prime digestion and boosting mood and productivity. And, as you already know, fasting impacts our body in plenty of favorable ways, but does intermittent fasting affect sleep? 

Continue reading to discover what might be keeping you up at night during fasting. 

How Does Fasting Work?

Fasting consists of abstaining from food (in some fasts also liquids) for specific periods throughout the day. Fasting can offer various health benefits, among them, the most popular, weight loss. The body may experience metabolic changes during fasting as it resources energy from stored fat reserves. 

Diverse types of fasting approaches adapt to unique lifestyles and objectives. They range in intensity and duration. For instance, the 20:4 fast is considered an intense fasting method because it has a 4-hour eating window, whereas the 14:10 fast is more relaxed, allowing for a 10-hour eating window that fits well into an everyday schedule. Other intermittent fast variations include alternate-day fasting (ADF), the 5:2 method, and the fasting-mimicking diet. 

Fastic can help you determine which fasting protocol is right for you. You can get a personalized fasting regimen by taking the Fastic quiz and answering straightforward questions about your eating habits, lifestyle, and objectives.

Why Is Sleep Important for Your Health?

Sleeping less than 7 hours at night regularly has been linked with poor health. Apart from being the time our body physically and mentally rests, sleep also plays a vital role in supporting other bodily functions, such as:

  • emotional stability and resilience to stress

  • brain function enhancement

  • hormonal balance involved in metabolism

  • muscle repair and tissue growth

  • strengthening of the immune system

  • regulation of blood pressure, heart rate, and inflammation

  • cells repair and rejuvenation

  • healthy metabolism and reduce risk of metabolic disorders

Not getting enough sleep or quality sleep elevates the chances of developing heart and respiratory problems, affects metabolism, mental clarity, and can even lead to weight gain. 

intermittent fasting and sleep

Role of Circadian Rhythm in Regulating Sleep-Wake-Cycles

Going to sleep at night and waking early in the morning didn’t simply happen because humans decided they had had enough of life by the time the moon came out. Our body’s sleep-wake cycle is regulated by something known as circadian rhythm. Circadian rhythm is the internal clock in our brain that governs cycles of alertness and sleepiness. It repeats roughly every 24 hours and is influenced by external cues like light and darkness. Thanks to this natural phenomenon, we feel awake during the day and tired at night.

Fasting and Sleeplessness: What Does Research Say?

Throughout the years, numerous studies and research have been done to better understand the correlation between intermittent fasting and insomnia. Let’s go over what some findings say about the influence intermittent fasting has on sleep.

Does Intermittent Fasting Improve Sleep?

A review published in the National Library of Medicine (NLM) examined various time-restricted eating and alternate-day fasting trials and their results regarding the influence of fasting on sleep. This review found that, while sleep quality remained unchanged in some trials, others showed improvement in sleep quality. It is important to note that individuals were already getting enough sleep at baseline (7 or more hours). 

Another study performed on healthy male individuals found that diurnal intermittent fasting increases the levels of orexin-A, a neurotransmitter tied to alertness, during fasting hours. This means that fasting may enhance alertness during the daytime, leading to a more restful sleep during the night. A separate study on the influence of intermittent fasting on the circadian pattern of melatonin under controlled parameters showed no significant changes in it.

Years of trials and research have demonstrated that fasting protocols lead to weight loss. Experts believe fasting is an effective method to improve sleep quality and quantity. According to a study by Johns Hopkins University, it was determined that sleep quality can be significantly improved with weight loss. 

Intermittent Fasting and Insomnia: Can Fasting Cause Insomnia?

You may experience difficulty sleeping during fasting, also known as insomnia. Insomnia is defined as difficulty initiating or maintaining sleep. The NLM review found that only one of the trials reported that participants experienced worse sleep latency and efficiency. A different study with over 1,000 participants examined the effects of fasting regimens lasting from 4 to 21 days. Researchers found that 15% of all participants reported sleep disturbances, the most frequent side effect.

Moreover, scientific research proves that difficulty sleeping during intermittent fasting can be due to irregular eating times. Eating in the evening or late at night can be too heavy for the stomach, affecting sleep quality and making it difficult to slip into slumber. Whether it's shortening eating windows or reducing calorie intake, fasting also puts your body under stress. This can encourage the production of cortisol, a stress hormone, which has been linked to poor sleep quality.

All in all, while study results are all over the place, research and evidence point to the fact that fasting has, for the most part, no effect on sleep. Nonetheless, how the body reacts to fasting will differ from person to person. Fasting might have a positive impact on someone but have a negative effect on someone else. 

Potential Benefits of Fasting for Sleep

Besides a healthy rest, fasting can also provide additional benefits, such as:

  1. Regulate the body’s internal clock, promising the body more consistent sleep-wake cycles.

  2. Balance hormone levels that impact sleep-wake cycles and sleep quality, such as melatonin, cortisol, and human growth hormone.

  3. Reduce inflammation and oxidative stress, promoting relaxation.

  4. Aid weight loss, leading to an improvement in sleep quality and reducing the risk of sleep-related conditions.

  5. Stabilize blood sugar levels, preventing energy crashes that can disrupt regular sleeping schedules.

Does Sleeping Count Towards Intermittent Fasting?

Unless you sleepwalk, it is a known fact that you don’t eat while sleeping. Therefore, yes, sleeping does count towards fasting. Sleep is optimal for your body to recover. Combining fasting effects and sleep allows the brain and body to rest and reset. Use the Fastic app to track your sleeping patterns and hours, helping you make informed decisions on modifications needed to improve your fasting approach.

Why Can’t You Sleep While Fasting?

A growling stomach might be the most likely reason you can’t sleep during fasting. You may experience hunger and discomfort mostly during the first days of fasting. But, besides hunger interfering with your sleep, there are other possible motives your sleep is being affected, including:

What Can Help You Sleep Better During Fasting?

If you are one of the unlucky individuals who have trouble sleeping while fasting, then you want to take note of the following tips to help you fall asleep faster and catch plenty of good quality z’s.

Help yourself achieve and maintain healthy sleep during fasting by:

  • Going to bed hydrated. Maintain adequate hydration levels throughout the day and before bedtime. Drink sufficient water and electrolyte drinks during fasting, especially if you enjoy exercising during fasting.

  • Maintaining a well-balanced diet: Providing your body with essential nutrients, like vitamins, will aid the production of sleep-inducing neurotransmitters. Also, balanced meals help stabilize blood sugar levels, preventing energy crashes.

  • Setting a fasting schedule that works for you: For some people, an earlier eating window during the day might be more effective, while eating later in the evening works better for others. Going to bed with a growling stomach will most likely give you a hard time falling asleep, and potentially even wake you up during the night. Try different eating windows throughout the day and determine which one works better with your body. 

  • Listening to your body’s signals: Pay attention to hunger cues and energy levels. If you suffer from pre-existing sleep disorders, you should be particularly cautious. Adjust your fasting schedule according to your body’s needs. Remember! Whether you fast for 6 hours a day or for two days straight, you will still reach your objectives, but an unhealthy body will get you nowhere. 

Sacrifice Your Midnight Snack, Not Your Sleep

Now that you know the relationship between intermittent fasting and sleep, you can assess the potential positive and negative effects intermittent fasting may have on you. Thankfully, there are innovative tools, like the Fastic app, to undergo a healthy and well-balanced intermittent fasting experience. Monitor your liquid intake, number of meals, fasting hours, and more, all in one place. Through Fastic’s all-in-one tool, you’ll make informed decisions to optimize your fasting and sleep.

Disclaimer: It is advised to speak with a health professional before beginning intermittent fasting or a diet program. There may be side effects for people with certain medical conditions.

With Fastic, millions of people have achieved their desired weight, overcome disease and regained their quality of life.

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