If you’ve just started intermittent fasting, you may feel like you have more energy to work out and perform your daily functions. You may even complain less about not getting enough sleep or feel like you don’t need the same amount of sleep as you used to. So, do you need less sleep while fasting? The answer to that question is no.
You don’t feel sleepy on fasting days because your body is pumping out cortisol (stress hormone) during your fasted state. If your blood sugar levels are too low or you’re under stress, your body will release more cortisol to convert stored glycogen to glucose, bringing your blood sugar levels back up without eating anything.
The increased energy while working out is due to the glycogen in the muscles being converted to glucose. This activates the muscles and enables us to fight or flee from a threat. However, since we don’t hunt for our food, the excess cortisol being produced adds to our stress load, resulting in sleep issues.
How Does Fasting Affect Our Sleep?
Although limiting your food intake for a certain period can do your health wonders, intermittent fasting has side effects, especially for your hormone health. This mainly affects people with adrenal fatigue, thyroid problems, and other issues related to chemical imbalances.
Sleep deprivation and insomnia are common drawbacks of the chemical imbalances that arise from intermittent fasting, so let’s look closely at fasting and sleep connection to determine if intermittent fasting is right for you.
Adrenal Hormones (Cortisol)
If you look at it from an evolutionary point of view, intermittent fasting was probably the norm when food wasn’t as readily available as it is now.
There’s a high chance that our paleo ancestors did go 12 to 16 hours without eating regularly and had lighter days when they ate less or nothing at all.
Therefore, it can be said that intermittent fasting is part of our evolutionary heritage, but it may not be the best wellness tool for everyone because fasting elevates cortisol levels.
Food deprivation increases cortisol levels which, in turn, increases vigilance. Again, this makes evolutionary sense. An animal with an empty stomach needs to stay alert for hunting and feeding opportunities.
Normal Sleep Architecture
Normal sleep architecture consists of light sleep, deep slow-wave sleep, and REM (dream stage) sleep cycles.
- Stage 1: This is where you start to doze off, which usually lasts just 1-5 minutes.
- Stage 2: Your heart rate starts to slow, and your body temperature drops.
- Stage 3: This is the transitional period between light and very deep sleep, characterized by 20 to 50% slow brain waves.
- Stage 4: This includes greater than 50% delta waves and lasts around 30 minutes.
- Stage 5: This is rapid eye movement or REM sleep, which occurs about every 90 to 110 minutes of your sleep, with mainly slow-wave sleep taking place in the first half of the night and REM in the second half.
During your sleep, the hypothalamus in your brain secretes corticotropin-releasing hormone (CRH), which binds with the CRH receptors in your anterior pituitary gland, releasing adrenocorticotropic hormone (ACTH).
ACTH interacts with the adrenal cortex, producing cortisol. Cortisol levels begin to rise within 2-3 hours of sleep and continue to elevate during early morning and waking hours.
Cortisol levels fall by bedtime and increase at night, reaching their peak just before you wake up. This acts as a wake-up signal, increasing your appetite and energy.
Sleep is a complex phenomenon that involves multiple hormones to maintain our body and health.
Here’s a summary of the hormones released during our sleep and how they assist the body:
- Growth hormone: For growth and tissue repair.
- Melatonin: Releases with increased darkness, and signals that the body needs sleep.
- Oxytocin: Peaks after 5 hours of sleep and may influence your dreams.
- Cortisol: Involved in immune response, metabolism, and stress response. Levels rise before waking up to increase hunger and wakefulness in the morning.
When Does Cortisol Become a Problem?
Throughout your sleep cycle, your body releases cortisol in different amplitudes. When your body is stressed, such as during a fasted state, high cortisol levels decrease your restorative slow-wave sleep and increase light sleep.
A common complaint among intermittent fasters is that they frequently wake up at night. In this scenario, your elevated cortisol levels may be responsible.
Your body produces more cortisol when you’re stressed, when your blood sugar levels are low, when you stub your toe or when you have too much caffeine.
When the body is pumping out high cortisol levels during fasting, the brain cannot tell whether our blood sugar levels are low or whether we are in a threatening situation. The brain cannot distinguish between low blood sugar and a potential threat, so it stimulates a stress response.
When the body releases too much cortisol, it’ll eventually produce more adrenaline, resulting in increased wakefulness. However, as the body produces increased amounts of adrenaline, it also sets you up for a quick burnout, thus resulting in adrenal fatigue and exhaustion.
Over time, this cortisol load can cause these health issues:
- Increased stress and anxiety
- Increased belly fat
- Hormonal imbalances
- Insulin resistance
- Type-2 diabetes
- Cardiovascular disease
- Weight gain
- Thyroid issues
- Digestive issues
- Chronic fatigue
- Weakened immune system
- Fertility issues
- Sleep problems, such as insomnia
During fasting, your body releases a neurotransmitter called orexin, also called hypocretin. Orexin keeps you alert, increases body temperature, makes you want to eat, and elevates your metabolism.
According to a study conducted by the University of Liverpool, low orexin levels in mice are linked to obesity, even when fewer calories are taken than usual.
Restricting your food intake activates hypocretin cells. Also, anything that stimulates the release of cortisol, such as reduced sleep, will further boost the release of orexin.
This increases your appetite. When you have high orexin levels in your body due to intermittent fasting, you’ll have difficulty going to sleep because the neurotransmitter increases alertness and wakefulness.
Furthermore, orexin expresses leptin receptors. Studies show that injecting mice with leptin (an appetite-regulating hormone) decreases their orexin activity. This shows that orexin is stimulated partly by declining leptin levels in the blood, and an increase in leptin, reduces the activation of orexin.
According to experiments, re-feeding brings orexin levels back to normal to a certain extent.
What’s the Role of Leptin in Sleep and Obesity?
The less you sleep, the lower your leptin levels. Leptin is an appetite-suppressing hormone, so lower levels may cause you to graze more, increasing your risk of gaining weight.
Furthermore, orexin stimulates your appetite and wakefulness and is activated through the increasing release of cortisol, which in this case, is from fasting.
The only way to feel tired and sleep is to lower your orexin levels by re-feeding. This sounds great, but this may not necessarily work for everyone, especially if their bodies are leptin resistant.
Having leptin resistance means that your body isn’t able to completely utilize rising levels of leptin after eating again following a fast.
People who may be leptin resistant and less likely to respond include anyone who is/has:
- Coming out of a yo-yo dieting system or severe caloric restriction
- Over-stimulated appetite
- Underweight due to their low leptin levels
- Eating disorders, such as binge eating disorder or bulimia
- Adrenal fatigue
Understanding Leptin Sensitivity
Your body has a “Stop eating” hormone called leptin that plays a major role in regulating your hunger and weight.
Leptin sends signals to the brain when your energy needs have been met during a meal while controlling your energy expenditure. A well-functioning leptin system improves brain function, performance, memory, mental sharpness, and mood.
However, not taking care of your leptin levels can come back to haunt you, causing leptin resistance. Fortunately, this can be reversed with appropriate diet and lifestyle modifications.
What Causes Leptin Resistance?
Many diets claim that consuming fewer calories and less fat or carbs are surefire ways of losing weight.
However, this strategy doesn’t last too long. With time, your caloric restrictions lower your leptin levels, slowing down your metabolism and making it increasingly difficult for you to lose any excess pounds.
Leptin imbalances can occur when you ignore its “stop eating” signals. Leptin is the hormone that lets you know when you’re full; continuing eating in the long-term despite feeling full can set you up for leptin resistance.
Overeating negatively affects your body’s ability to determine whether your fat levels are too high. What’s worse is that constantly ignoring your leptin signals can also cause the leptin receptors in your brain to become numb, preventing you from feeling full in the future.
Leptin resistance is a red flag for insulin resistance, as leptin plays a critical role in monitoring insulin sensitivity. According to Obesity Research, insulin sensitivity alone can contribute to obesity and type-2 diabetes.
Researchers believe that frequent exposure to stressors and toxins can increase your risk of leptin resistance.
How to Improve Leptin Sensitivity
Short-term fasting can reduce leptin levels. If you feel your leptin sensitivity can use some TLC, do the following:
- Have a breakfast rich in protein and healthy fats to promote hormone production
- Reduce your intake of refined carbs, such as white flour and sugar
- Finish eating meals 4-5 hours before you sleep
- Consume a diet rich in fiber and protein.
- Increase your intake of anti-inflammatory omega-3 fatty acids, such as avocado, fish, and nuts.
How to Improve Sleep While Fasting
The stress associated with fasting can make your brain more alert.
From an evolutionary perspective, our ancestors needed to stay alert for any hunting opportunities. However, the wakefulness that results from intermittent fasting can keep us from falling asleep at night.
Like most negative effects of fasting, insomnia is worse during the first few days and improves as you continue for several days. However, for some people, insomnia remains an issue during fasting.
If you’re having a hard time falling asleep on fast days, the following strategies can be beneficial:
Calories Before Bedtime
Ideally, you shouldn’t eat before bedtime, especially during intermittent fasting. However, if you’re having trouble falling asleep, consuming high protein or high-fat snacks, such as yogurt, warm milk, or a cube of cheese can help.
Good Sleep Hygiene
Sleep hygiene involves taking the right steps to prepare for sleep, including:
- Avoid looking at a screen close to bedtime. This involves turning off your television, shutting down your computer, and avoiding using your tablet, cell phone, or any other smart device.
- Keep your bedroom cool and dark. Our bodies are designed to sleep during the night. So, we release more melatonin when it is cool and dark.
- Use your bedroom for sleep and intimacy only. Don’t use your bedroom for screen-based entertainment, work, hobbies, or anything that requires you to be mentally active.
- Don’t work out close to bedtime. This increases your alertness and stress, preventing you from falling asleep.
- Avoid sleeping in late in the morning. Instead of trying to take naps and sleeping in extra to make up for lost sleep at night, have a set sleep schedule.
- Comfortable bedding. Make your bed as soon as you get up. A bed that’s made is more inviting than an unmade bed which can trigger stress and reduces feelings of relaxation.
Constantly staying in low light indoors can impact your circadian rhythm and the hormones that regulate sleep.
Even a brightly lit room is no match for the natural brightness of the sun. Getting up and leaving the house for some sun can help maintain your biological clock and promote better sleep.
Furthermore, sun exposure promotes vitamin D production in the body, which plays a role in numerous bodily processes, including sleep.
A study by Northwestern University found that individuals who spent more time outdoors during the early morning hours tended to weigh less.
Some effective sleep supplements include magnesium and melatonin.
Magnesium deficiencies are common as this mineral plays a crucial role in regulating sleep. Some forms of magnesium are better absorbed than others. For insomnia, magnesium citrate is recommended.
Taking melatonin on days when you’re fasting can help you get better sleep and re-establish your sleeping patterns. Melatonin is a sleep hormone that’s naturally produced in the body to support sleep.
Don’t shy away from smaller doses such as 0.5 mg. You can increase your dosage slowly if a lower dose doesn’t work for you. Work your way up to 3 to 5 mg, if needed.
Less is more when it comes to taking melatonin supplements.
Turkey is packed with tryptophan, an amino acid that promotes serotonin and melatonin production. Foods containing tryptophan include poultry, eggs, cheese, pumpkin seeds, sesame seeds, mung beans, and kidney beans.
Reduced Glucose Levels
Following a heavy meal, your blood sugar levels spike. This stimulates the release of insulin to bring blood glucose levels back to normal.
However, most of the time, the increased surge of insulin causes blood sugar to drop lower than normal, resulting in an energy crash and increased cravings for sugar.
If hunger and increased cravings keep you awake, avoid blood glucose fluctuations throughout the day. To do this, avoid adding too many sugars, artificial sweeteners, and refined carbs to your meals.
Stay away from high glycemic foods and increase your intake of protein, good fats, and fiber. If you’re craving something sweet, adding some protein or good fat will lower its glycemic value and increase your satiety.
No Coffee After Midday
Caffeine remains in your system for up to 8 hours, countering the effects of melatonin.
Stop drinking high-caffeine beverages after noon to prevent caffeine from keeping you up in the night. Drink a caffeine-free alternative such as coconut water if you require a quick boost.
Sleep deprivation during fasting stages in the night may increase your urge to nap more in the daytime. However, taking long, frequent naps can throw your natural circadian rhythm.
The solution is to take one short nap. Have a set nap time for any day you need a quick energy boost. Our alertness usually dips between 1 pm to 3 pm, so set your naps for this time of the day.
Keep your naps to 10 to 15 minutes. When you sleep for longer than 20 minutes, you enter deeper stages of sleep. Waking up from deep sleep can leave you feeling groggy and lethargic.
Intermittent fasting alone won’t solve your body weight, blood sugar, or inflammatory issues. Not taking the correct steps to improve your sleep and optimize your fasting can prevent you from enjoying the benefits of this lifestyle.
You need to practice the right sleep techniques while incorporating measures to keep your leptin sensitivity in check. Allow your body to rest, and include quality protein and good fats from fish, avocado, olive oil, and nuts to promote the healthy production of sleep-promoting hormones.