Intermittent Fasting and Sleep
Intermittent Fasting (IF) is a hugely popular dieting method. After polling our Instagram follower’s nutrition questions, 70% of them were IF related. Coincidentally, I have been an accidental intermittent faster for two years.
Intermittent fasting and sleep have the power to transform your mind and health. Given my engineering background, I am continually running experiments to optimize my sleep and intermittent fasting plan.
In this article, I’ll share my intermittent fasting before and after story as well as my experience helping hundreds of couples start intermittent fasting while focusing sleep quality in parallel.
intermittent fasting and sleep
As we tell all of our clients if you’re focusing on a diet to lose weight, but ignoring sleep, you’re wasting your time. The same goes for an intermittent fasting diet. Fortunately, sleep does count as fasting, and it’s the secret weapon to being successful with IF.
Let me start by sharing my intermittent fasting sleep story. After that, we’ll dive into topics on fasting and sleep, including some of the sleep problems that intermittent fasters experience.
For example, we’ll cover questions about trouble sleeping or difficulty falling asleep, how to sleep when you’re hungry (hint- you shouldn’t), and what to do when you can’t sleep while intermittent fasting.
If you’re more interested in learning how to start intermittent fasting successfully, you will find our guide to intermittent fasting more helpful.
Intermittent Fasting Before and After
For four years, I slept only 6-hours a night. My typical day was waking up at 5 AM for a workout, eat my first meal at 6 AM, and my last meal at 11 PM before bed, consuming a total of three meals and two snacks during 18 waking hours.
On weekends or while traveling, if I missed a meal in that 18-hour eating window, I was not a happy camper. My self-control over my hunger was weak.
When a hunger pang struck, it was like a switch flipped. One word: hanger. I needed to eat immediately and would go for the fastest meal or snack (rarely the healthiest). Although I was health-conscious, these incidents made my diet more volatile.
In addition to experiencing frequent hanger, I also suffered from extreme drowsiness, most commonly after meals.
What I have described here is the opposite of intermittent fasting.
In March 2018, I quit my job as an engineer to travel as a digital nomad. This decision was a timely lifestyle change since I had sleep deprived myself for many years.
I was one of the many people who, due to sleep debt and workload, experienced burnout and low testosterone in their 20s. It was extremely eye-opening, and the importance of sleep humbled me. Therefore, when I quit my job, quality sleep was my highest priority.
Fortunately, increasing my sleep made the transition to intermittent fasting much easier, because sleep does count as fasting.
Now, nearly two years later, I sleep 8-9 high-quality hours per night. When I wake up around 8 AM, I work out, read, and eat breakfast between 10 and 11 AM.
I consistently eat three large meals a day (I am never hungry in the morning or at night), and follow a 16 hour fast, or the 16/8 plan. I finish my 8-hour eating window after dinner between 6 and 7 PM.
I started out gradually, eating for 10 hours and fasting for 14 hours. It wasn’t easy at first (more on that later). However, my goal to get more sleep almost accidentally aligned me with a 16/8 intermittent fasting plan.
Ironically, this 16 8 window was the exact opposite of what it was the year before. So, what were the benefits of intermittent fasting and focusing on quality sleep? I am glad you asked.
Intermittent Fasting and Sleep Benefits
In retrospect, my health and well-being improved tenfold. I maintain a healthy weight and never have fatigue during the day or after a meal. My hanger is no longer an issue, and I have full control of my hunger. The quality of my sleep is incredible.
One surprising benefit is that I eat slower, which is beneficial for digestion and weight management. Eating slower was one of my New Year’s Resolutions in 2018. Intermittent fasting helped me succeed.
When I wake up in the morning, I feel focused and ready to hammer out my day’s to-do list. I drink the best coffee and prepare it in a French press because I enjoy the ritual, not because I need it to function in society.
I can’t say what percentage of these improvements are due to overcoming sleep deprivation or becoming an intermittent faster. However, I can proclaim that both are closely related and have been paramount to my new-found physical energy and mental vitality.
Both intermittent fasting and sleep have a similar cleansing effect on our brain and body.
When you aren’t fasting, your body and brain have to process what you’re ingesting. While fasting, your body and brain can focus on detoxing and distributing nutrients properly to optimize your physical and mental performance.
Similarly, this process also happens while you’re sleeping. When you don’t sleep enough, your brain doesn’t have adequate time to store and process memories, for example. Instead, brainpower is processing the stress of the day.
In short, the benefit of quality sleep and intermittent fasting is a higher functioning mind and body.
By focusing on intermittent fasting and sleep at the same time, the diet has seamlessly worked itself into my lifestyle. I would not recommend IF to anyone who is not committed to sleeping 7-9 hours a night.
Intermittent fasting is challenging at first. However, if you transition gradually and eat right, intermittent fasting should not impact your sleep. Instead of making you sleep less, it should help you sleep more.
While gaining muscle and losing weight is a possibility when you follow intermittent fasting, that shouldn’t be the focus of your new diet. Instead, focus on the opportunity to improve mental clarity and energy levels.
Intermittent fasting makes me feel highly focused throughout the day, and my energy levels are more balanced. I avoid the cycle of feeling starved, overeating, and then crashing.
questions about sleep and intermittent fasting
Answers to the following questions are based on my personal experience, the experience of clients, and scientific studies. Additionally, the content was reviewed by multiple doctor and nutritionist friends on our newsletter.
Does sleep count as fasting?
Your intermittent fasting window includes sleep. Sleep is considered fasting. Therefore, the more you sleep, the less you have to be awake in a fasted state. That makes it easier because you’re unconscious while your stomach is growling.
How does IF directly improve your sleep quality?
Studies suggest that intermittent fasting positively influences your circadian rhythm and your body’s ability to manage REM sleep. Both of which are critical to falling asleep, getting quality sleep, and waking up well-rested and ready for the day ahead.
Some people report not sleeping well while intermittent fasting. We’ll cover some common causes. Intermittent fasting should not cause sleep problems. However, if two months of implementing and experimenting with what you learn is this article proves unhelpful, it might not be the best eating plan for you.
How does fasting improve your health?
Most importantly, while fasting, your body secretes less insulin and more human growth hormone. These hormonal changes are one of many evidence-based benefits of intermittent fasting. More HGH means your brain and organ tissues are better maintained and strengthened.
For intermittent fasting beginners, what’s easy?
For myself, and clients that we’ve worked with, many aspects of the IF diet came naturally.
1. Sleeping more
Firstly, the longer sleep window makes transitioning to a shorter eating window more easily. You’re asleep while your stomach is growling.
2. More encouragement to eat healthy
The transition to a shorter eating window is easier for individuals eating a healthy diet and staying hydrated. If you’re lacking nutrients and calories, your transition is going to be much harder.
Use your new IF plan to further motivate you to eat healthier. A healthy diet consists of fiber-filled carbs, healthy fats like nuts and avocados, high-quality animal products, and as many vegetables as possible.
3. Working out
I was apprehensive about working out on an empty stomach. Fortunately, it was not a problem at all after a short time. I even noticed my workout performance increase.
There were a couple instances when I became dizzy while working out in a fasted state. I stopped, drank water, and ate a banana. After a few minutes, I was ready to go again. As always, listen to your body and avoid deprivation.
4. Don’t be too strict
The most important thing for beginners is to listen to your body and adjust accordingly. For example, if a 16/8 plan is too extreme, begin with a 12/12.
Or, if you’re consistently going to bed hungry while intermittent fasting, the short-term solution is a bedtime snack, while the long-term goal is to eat more food.
For IF beginners, what’s hard?
The hardest part for most is the hunger in the morning and before bed. During the first two months of IF, I woke up feeling starved. During this time, it’s essential to adjust gradually. That’s why I started by eating for 10 hours and fasting for 14. Drinking water or coffee in the morning helped too.
Also, fight through the hunger by being mindful. Focus on the positive side of hunger, which is that you’re allowing your body time to processing toxins and optimize mental and physical performance.
Additionally, focus on increasing your self-control. By fighting through hunger, that means you are calling the shots, not your grumbling stomach. This attitude of self-control spills into all areas of your life. For example, eating the proverbial frogs on your goal-oriented to-do list.
Battling hunger is especially hard if you are trying intermittent fasting and waking up early, like at 4 AM. People always ask me how to do intermittent fasting when you wake up early.
If this is you, I recommend waiting to eat your first meal for 5-6 hours, and eating your last meal 3-4 hours before bed. To make intermittent fasting work with an early start, it’s critical that you go to bed early. That could mean that you’re having dinner at 4 PM.
2. Not eating enough
When I started IF, I constantly double-checked my calories. I made sure I was eating the correct amount of calories in my shorter eating window. This is hard at first because you might have to eat when your body isn’t screaming at you, “I’m hungry!”
If you don’t know how to calculate your calories, look at the instructions for our 30-Day Weight Loss Challenge. People who start intermittent fasting have a tendency to eat too few calories.
At first, I had to schedule my meals because I wouldn’t be hungry yet. Try setting an alarm on your phone to remind you when to eat.
People don’t lose weight intermittent fasting because they are eating less food. The IF rules say that you eat the same amount of calories, just in a shorter time.
Restricting calories will cause a weight loss plateau, or, even worse, make you gain weight.
3. New Schedule
Starting intermittent fasting requires a schedule change. For most, that means a new morning ritual. Adjust your wake up, workout, and breakfast time and know that you might not nail it on the first try.
I recommend working out first thing, drinking a lot of water, and having an intermittent fasting distraction drink while you complete your most daunting to-do list tasks. Most intermittent fasters report extremely high focus and productivity in the morning.
A distraction drink is something to fend off your hunger and wake up your digestive system. As long as your drink is less than 50 calories, that’s not breaking your fast, according to intermittent fasting rules. We prefer to drink black coffee or the below digestive drink.
Morning digestive drink:
- One cup of hot water
- One half a lemon squeezed (excites digestive enzymes)
- Two caps full of apple cider vinegar (balances pH levels in the gut for healthy bacteria growth)
- A pinch of cinnamon (to stabilize blood sugar levels).
How Can I Improve Sleep While Intermittent Fasting?
Trust me. I know how hard it can be to fall asleep when you’re hungry. If you’re new to intermittent fasting and having difficulty sleeping or waking up at night, the following will help. The goal with intermittent fasting, as it was for me, should be to get more and better quality sleep.
1. Find what works for you
We’re all unique individuals. Therefore, our body’s response to IF can vary. Instead of getting caught up in studies, facts, or what worked for your friend, engage in self-experimentation.
Try various eating windows. If you’re eating in a 6-hour window and not sleeping well, scale back to a 10 or 12-hour window. Your cortisol levels may become too high with such a long fast. Excess cortisol makes it hard to fall asleep and sleep soundly.
Also, keep a journal of what you’re eating, when, and how you sleep. Then, over time, you can determine how the foods you eat are affecting your sleep.
Lastly, try adjusting your bedtime. Listen to your body, and when your circadian rhythm nudges you to go to sleep, do it. If you’re too hungry to sleep, maybe you’re staying up too late.
Sleep is complex. If you’re intermittent fasting and can’t sleep, there are likely many factors, not just your new eating schedule. Could it be possible that you are spending too much time looking at a screen? Or are you drinking too much alcohol?
2. Drink more water
Keeping hydrated will help you avoid hunger pangs while improving your mood and energy level. Dehydration negatively affects sleep. I know this first-hand from a hydration and sleep experiment I conducted while living at high elevation.
Elevation exponentially worsens the effects of dehydration on sleep, so it was a perfect environment for this study. The conclusion: dehydration yields a more restless night sleep followed by drowsy mornings.
Yes, you can drink water while intermittent fasting. And, you should. Lots of it!
3. Monitor your meals
Intermittent fasting and sleeping will both deliver optimal results when paired with healthy food. Again, keep a journal of what you’re eating and how it makes you feel. Some people find that dairy products make them sleep less soundly, especially when consumed at night. As you journal, look for patterns like that.
You need to run your own tests, but a lot of people sleep better when they have a big breakfast and a smaller dinner. Studies have also shown that this is beneficial for weight loss. It’s essential to make sure you’re not still digesting when it’s time for bed. Eat dinner 3-4 hours before bed.
And what about carbs? In the same day, I listened to a podcast by a nutrition expert who said, “Carbs are energy, and you don’t need energy before bed,” and read an article from a reputable source that said, “Carbs will increase your serotonin production and therefore help you sleep.”
The point is, who knows what is best? This is why self-experimentation and trial and error is crucial. I am vegetarian, and the healthy, fiber-filled carbs I eat for dinner do not cause difficulties sleeping.
4. Take a holistic approach
Sleep science has become much more conclusive in the last 20-30 years as MRI scanning technology becomes more advanced. Scientists can run tests and then collect data on how the human brain responds. There are certain things we now know conclusively.
First, don’t work on your laptop or use any screen (TV included) before bed. Your brain needs time to wind down. Instead of scrolling social media on your phone, read a book or stretch with some couple’s yoga poses. It’s unlikely that intermittent fasting causes insomnia. Alternatively, screen time is a significant contributor to the rapidly increasing cases of insomnia.
Second, make your bed room a sleep sanctuary. Invest in a sound machine and a sleep mask (this is the most comfortable and blackout mask we have found). We use blackout curtains at home, but when you travel a lot, a sleep mask ensures that it’s pitch black in every room you sleep.
Third, if you’re inclined to learn more about the processes and the products that we have used to optimize our sleep, check out our article on the importance of sleeping well. We also highly, HIGHLY recommend you read the book Why We Sleep.
What are good intermittent fasting hours?
A lot of experts on the relatively new topic say that a 14-hour fast (10-hour eating window) is the minimum for IF to work. In my opinion, anything beyond an 18-hour fast (6-hour eating window) is too extreme and too hard to sustain.
But, you can still reap the benefits of intermittent fasting by restricting yourself to a 12-hour eating window. As a beginner, especially for females, this is an excellent starting point.
What are the benefits of IF?
There are many scientifically proven health benefits that intermittent fasters enjoy, such as maintaining healthy body weight, balancing blood sugar levels, providing insulin resistance, and reducing the risk of diabetes, one study shows.
There are also scientifically proven sleep benefits. In one pilot study, results showed that short-term fasting reduces the frequency of awakening and disruptive body movements, yielding a more sound night sleep.
Is Intermittent Fasting or Sleep More Important?
Hands down, sleep. Sleep is critical for every function of our mind and body. Again, if you haven’t read the book Why We Sleep, by Matthew Walker, you should. It will change your mindset from “I’ll sleep when I am dead,” to “I’ll sleep 8-hours every night, so I don’t die young.”
It’s true. I used to feel guilty about sleeping since it took time away from my side hustle. Now I cherish it and know that prioritizing it is the smartest use of my time.
If you prioritize sleep, intermittent fasting is a natural progression. If you prioritize intermittent fasting and not sleep, you won’t get results.
That’s because adhering to your window, avoiding cheat foods, limiting alcohol, and having the energy to celebrate progress will become nearly impossible.
Can I Lose Weight or Gain Muscle with IF?
Yes, science shows that with intermittent fasting you can lose weight and gain muscle. In addition to higher production of human growth hormone (HGH) and increase metabolism, your body and brain have more time to use the nutrients you ingest to optimize your health.
Additionally, studies show that intermittent fasting improves our body’s ability to metabolize body fat. Therefore, if you are eating well while intermittent fasting, you should see weight loss.
Conversely, if you are not eating healthy foods consistently or drinking too much alcohol, don’t expect to lose weight solely because you adjusted your eating window. These factors are also contributing to why you can’t sleep while intermittent fasting.
My goal with intermittent fasting was to gain some muscle mass. I needed to eat a lot of calories in a short time to achieve this goal. I have gained (and maintained) muscle mass by doing significantly less work.
Before I prioritized sleep and started intermittent fasting, I would weight lift 5-6 days per week for 45-minutes. Now I lift only 3-times per week (only with resistance bands) for 30-minutes and fill in the rest of the days with cardio and yoga.
Regarding exercise, I am getting more bang for my buck now that I am intermittent fasting.
Thanks for reading. Leave your thoughts in the comments!
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Hey we're Ryan and Alex
The creators of Ryan and Alex Duo Life. We are a husband-wife duo and “lifestyle engineers.”
After eight years working in the corporate world, originally as engineers, we left our high-powered jobs to tackle our true passion — helping couples engineer their best lives.
The synergy of our engineering minds and ten years of health coaching experience produced Ryan and Alex Duo Life. Our mission is to help you transform your bodies, minds, and relationship, as a couple.