Intermittent fasting and sleep. The effects and everything you need to know

Intermittent Fasting and Sleep: What You Need To Know for Better Sleep

Written by: Alec Tremaine

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Time to read 6 min

You've heard all the buzz about intermittent fasting for weight loss and overall health. But have you considered how intermittent fasting and sleep affect each other? Many people find that intermittent fasting leads to better sleep, but it's a bit more nuanced than that. It turns out the connection between intermittent fasting and sleep is a little more complex. By the end of this, you'll be well-equipped to silence that growling tummy and catch some quality Z's.

Understanding Intermittent Fasting and Your Circadian Rhythm

Brain, clock and circadian rythm

Let's talk about what happens when you practice intermittent fasting. Intermittent fasting takes your body on a journey to burn stored fat for fuel, breaking free from the constant reliance on carbs and sugars from the food you eat. This restricted eating pattern isn't just about energy management, but also aids in weight loss, overall health, mood, and - yep, you guessed it - sleep!


Your body's internal clock or circadian rhythm, is just like a watch, ticking away behind the scenes to regulate your sleep, hormones, and cell renewal. Intermittent fasting can be the nudge that sets this watch to a new rhythm, by fine-tuning your bodily functions and overall health. Timing your fasts with your natural rhythms may be just what your body needs to jumpstart weight loss and ramp up metabolic health.

The Hormone Connection

Melatonin hormone and sleep hormone over woman in bed

Ever notice how your hunger cravings seem to strike around the same time each day? Thank your circadian rhythm. Hormones like ghrelin and leptin, which alert us to our hunger or satisfaction, are sensitive to the influence of this regulator, which steers their production and release. When you eat, these hormones fluctuate predictably throughout the day and night.


Your body has a natural response to hunger, and it's triggered by hormones that kick in at specific times of the day. By fasting intermittently, you can fine-tune your eating schedule to match your body's natural rhythms, making hunger easier to control. This very balance is a lifesaver for those prone to raiding the fridge in the dead of night or waking up with a rumbling tummy.


A critical hormone for sleep regulation is melatonin, which ordinarily increases about two hours before your usual bedtime. Research suggests that, in humans, melatonin production happens at specific times, usually between 11:00 p.m. and 3:00 a.m. Melatonin signals to your body that it's time to wind down for sleep.


If you've been curious about how intermittent fasting influences melatonin, you're not alone – scientists are still on the case. But so far, it looks like this approach might just reset our internal rhythms and gear up melatonin production. And better melatonin production means you'll likely fall asleep more easily and potentially enjoy more restful sleep. Intermittent fasting's advantage shines bright in its simple yet powerful potential to rescue our sleepy lives from the damage of mindless snacking.

Intermittent Fasting and Sleep Quality: The Good and The Bad

Intermittent fasting isn't a magic sleep solution; its impact can vary from person to person. You may notice you fall asleep faster and wake up feeling more refreshed. When blood sugar levels remain steady throughout the night, it's like hitting the snooze button on those abrupt energy crashes that otherwise shock you awake.


Intermittent fasting, and alternate-day fasting in particular, seems to rouse the body's production of human growth hormone, according to some fascinating studies. Our bodies rely on  HGH  to grow, repair, and regenerate cells, and the benefits don't stop there: when levels are high, you can bet on a more rejuvenating sleep cycle. The proof isn't quite there yet - more studies need to be conducted to confirm whether intermittent fasting really does boost HGH and improve sleep quality.


That said, adjusting to an intermittent fasting schedule can take time, and you might initially experience some sleep disturbances, especially during the first few days or weeks. The moment you switch up your eating habits, your body responds by going into adjustment mode. You may experience difficulty falling asleep or waking up more frequently during your fasting hours. Don't give up! Stick with it, and your sleep should regulate itself as your body adjusts.

Tips for Improving Your Sleep While Intermittent Fasting

Couple sleeping in bed comfortably after fasting

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Are you starting an intermittent fasting journey and worried about its impact on your sleep? These tips can help:


  •  Ease into intermittent fasting: Don't jump into a strict fasting schedule right away. Imagine your body getting a " Ramp-Up" notice, slowly adjusting to the new pace, and as a result, a peaceful night's sleep becomes more likely. For example, you can progressively push back your dinner time by an hour every few days until you reach your desired fasting window.


  •  Stay Hydrated:  This advice seems simple, but many people don't realize how important it is to drink plenty of water throughout the day, even while fasting. Sleep is just one of the many benefits you'll reap when you make hydration a priority - it's like hitting the reset button on your entire body. Remember that fluids like broth and unsweetened tea are acceptable while fasting.


  •  Don't go to bed ravenous:  If you find yourself feeling overly hungry before bed while intermittent fasting, it's perfectly fine to have a light, low-calorie snack to curb those hunger pangs and help you drift off easier. To tame your hunger without spiking your blood sugar, reach for protein-packed or fiber-filled foods.


  •  Create a relaxing bedtime routine:  As bedtime approaches, trade in your screens for a calming ritual - try sipping herbal tea, practicing gentle yoga, or simply savoring the silence. Silencing your racing thoughts and calming your physical tension can lead to a more restful night's sleep. It's best to avoid screen time at least an hour before bed since the blue light emitted from screens can mess with your sleep rhythm.  Studies have shown that blue light has a direct effect on quality of sleep and sleep duration.


Intermittent Fasting and Specific Sleep Issues

Woman sleeping with sleep apnea mask on after fasting

Intermittent fasting appears to have potential benefits for various sleep issues. Research is ongoing, but so far we've discovered that:

Intermittent Fasting and Sleep Apnea

Sleep apnea, a condition characterized by pauses in breathing during sleep, is often associated with obesity. Since intermittent fasting can be an effective weight-loss tool, it may indirectly improve sleep apnea symptoms by helping individuals achieve and maintain a healthy weight.

Intermittent Fasting and Stress Hormones

Intermittent fasting may also influence sleep by affecting stress hormone levels, such as cortisol. Elevated cortisol levels can interfere with sleep. Believe it or not, brief periods without eating may actually whip cortisol into shape, meaning you sleep like a baby.

Intermittent Fasting's Impact on REM Sleep

REM sleep, characterized by rapid eye movement and vivid dreams, is crucial for memory consolidation and emotional processing. What we know about intermittent fasting's impact on REM sleep is severely lacking. As recent studies exploring calorie restriction suggest, fasting intermittently for short bursts could be the answer to getting more quality REM sleep. At the same time, conflicting evidence emerges, implying that our bodies may react in the opposite way, especially when we're still finding our footing with a new fasting approach. Figuring out what happens to REM sleep when you start intermittent fasting isn't a one-and-done deal; it takes ongoing research to tease out the long-term effects.


One positive correlation between intermittent fasting and better REM sleep can be found with the lack of alcohol in the body. During states of intermittent fasting, you are drinking!  Alcohol and sleep are like oil and water - they don’t mix well, and your REM sleep will suffer. 

Don't Let the Risks Catch You Off Guard

Intermittent fasting may bring advantages for sleep and overall well-being, but it's crucial to consider the flip side - potential pitfalls that can affect specific groups. Here's a closer look:


 Individuals 

 Potential Risks 

Pregnant or Breastfeeding Women

Intermittent fasting during these periods may not be safe, as it could potentially deprive both the mother and the baby of essential nutrients.

Individuals with Diabetes

Fasting can lead to dangerous drops in blood sugar levels, especially for those on diabetes medication.

Those with a History of Eating Disorders

Intermittent fasting could trigger disordered eating patterns in susceptible individuals.



People are puzzles, and what completes one picture might leave another incomplete. So you want to shake things up with intermittent fasting or a new diet? Pump the brakes and get your doctor's okay before making any drastic changes. A doctor or medical professional will help you decide if intermittent fasting is right for you and provide you the guidance you need through the process.

Conclusion and final takeaways

Sleeping better and feeling more alive are just two of the potential perks of embracing intermittent fasting as a conscious choice, rather than a trendy novelty. Catch the subtle signs your body sends you – like hunger pangs or fatigue – and let them guide you towards creating a plan that works in perfect harmony with your lifestyle, sleep schedule, and eating habits, all with the expert input of a medical professional.



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Alec Tremaine

Health and wellness enthusiasts focused on sleep and performance for longevity and better health.

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