January 02, 2021 10 min read

Sleep is a vital physiological process that occurs in most living organisms, including simpler life forms, such as single-cell organisms, which exhibit patterns that resemble sleep.

Unfortunately, most people take sleep for granted since it’s a passive activity that doesn’t require any effort. However, once sleep gets disrupted, a myriad of health problems arise, which could be quite devastating to the personal and professional lives of people.

While sleep is important for everyone, athletes are more susceptible to the consequences of poor sleep quality since their performance and recovery is highly dependent on how well they sleep.

Athletes who engage in high-intensity workout plans, such as CrossFit, are even more likely to witness poor sleep-related issues, including muscle atrophy, asthenia (i.e., energy drainage), and lack of focus while training.

In this comprehensive guide, we will discuss the primary driver of sleep – the circadian rhythm –, the importance of sleep for CrossFit athletes, and how to improve sleep quality.

By the end of this piece, you will be equipped with all the knowledge you need about the process of sleep and how to improve it.

If you are in a hurry and just want to know what to do to improve your sleep and recovery, check out this article:

7 Quick Hacks to Improve Your Sleep

The circadian rhythm

The circadian rhythm refers to a 24-hour (almost) cycle that regulates sleep based on external output (i.e., light).

The primary function of this biological clock is to control the sleep-wake cycle by secreting an important hormone known asmelatonin, which is responsible for inducing drowsiness and sleep.

Alongside the circadian rhythm, different parts of the brain (e.g., hypothalamus) work in synchrony to follow the instructions of our biological clock in order to induce sleep or wakefulness.

When the circadian rhythm is working properly, it promotes consistent, restorative, and refreshing sleep. However, any disruption to this clock leads to dire consequences, including insomnia, hypersomnia (i.e., excessive sleep), and other advanced/delayed phase disorders.

How does this system work?

The circadian rhythm responds to an area of the brain known as the circadian pacemaker located in thesuprachiasmatic nucleus (SCN) –a group of cells that are part of the hypothalamus gland–. At different times of the day, this nucleus sends electrical and biochemical signals to the body to regulate all sorts of sleep or wakefulness activities.

The primary factor that triggers the function of this nucleus is light that comes from the external environment.

Sunrise Light for Circadian Rhythm

This is why when you engage in certain social activities, exercise, or experience extreme temperatures, the master clock (suprachiasmatic nucleus) might get confused, disrupting your sleep-wake cycle.

How does the circadian rhythm affect sleep?

Generally speaking, when light hits certain receptors inside the eye, the master clock sends signals to generate a state of alertness to keep you awake.

As light becomes dimmer, the production of melatonin skyrockets, which exerts its action on several parts of the brain, leading to a general feeling of drowsiness.

In the absence of the master clock’s signaling (i.e., the sufficient production of melatonin), the person may find it extremely challenging to fall asleep or is likely to experience shallow, fragmented, and poor sleep quality.

Moreover, studies found that a disrupted circadian rhythm increases the risk ofobstructive sleep apnea, where the patient goes through repeated pauses of breathing during the night, which could be devastating for CrossFit athletes.

How does the circadian rhythm get disrupted?

Depending on the etiology (i.e., underlying cause), the disruption of the biological clock could occur for a short or a long period. Researchers refer to these conditions as circadian rhythm sleep-wake disorders (CRSWDs).

Some of these conditions include:

  • Jet lag disorder
  • Shift work disorder
  • Advanced sleep phase disorder
  • Delayed sleep phase disorder

Now that we’re familiar with the general function of the circadian rhythm, let’s briefly discuss the most common types of sleep disorders in CrossFit athletes:

Hypersomnia (i.e., excessive sleep)

You may have noticed that you are sleeping extra hours during the night, only to stay in bed all day long. 

At first glance, it may seem like you’re just getting some rest because you feel tired; however, and oftentimes, hypersomnia is a subtle sign of sleep abnormalities.

Therefore, and just like you are keeping track of your CrossFit workouts and diet, you may want to pay more attention to your sleep schedule.


For most people, insomnia is synonymous with difficulty falling asleep; however, theDiagnostic and statistical manual of psychiatric disorders V (DSM-V)classifies both insufficient sleep and difficulty maintaining it as types of insomnia.

Here are some signs and symptoms associated with insomnia:

  • Difficulty falling asleep
  • Difficulty maintaining sleep
  • Tiredness and drowsiness during the day
  • Poor physical performance during workouts
  • Non-refreshing sleep 
  • Distractibility and reduced concentration
  • Irritability 

The most common type of this disorder in athletes is acute insomnia, which lasts for several nights to weeks and can often be attributed to certain life events, such as stress and anxiety (e.g., upcoming competition).

On the other hand, we have chronic insomnia, which must occurat least 3 nights a week for longer than 3 months to be eligible for this definition.

Chronic insomnia is challenging to deal with, especially since the underlying cause is usually unidentified.

Sleep apnea

Obstructive sleep apnea (OSA) is commonly seen in all types of athletes, manifesting as brief and repeated pauses in breathing during sleep.

The medical literature states that the duration of pauses must beat least 10 seconds to qualify for this definition.

The primary defect in OSA is thelaryngeal muscle failure that cannot keep the airways open, leading to temporary apnea.

This condition leads to serious complications, including cardiovascular disease, metabolic syndromes, and neurocognitive deterioration. Additionally,athletic performance gets severely impacted.

According to theNational Sleep Foundation, more than 18 million Americans suffer from sleep apnea in its two forms:

  • Obstructive sleep apnea 
  • Central sleep apnea

Keep in mind that OSA is extremely under diagnosed, with some estimates stating that more than 80% of individuals with this condition have yet to be diagnosed.

One of the main obstacles doctors come across when dealing with a sleep apnea patient is the difficulty of posing the diagnosis.

Today, thegold standard of OSA diagnosis is to use polysomnography (PSG), which measures various vital functions (e.g., heart rate, respiratory frequency, muscle movements) to identify any abnormalities in the breathing patterns.

The importance of sleep for performance

As a CrossFit athlete, sleep optimisation is crucial for several reasons, including muscle growth and repair, performance, and energy production. Moreover, getting sufficient hours of sleep promotes better cardiovascular health and immune system function, which all contribute to your performance as an athlete.

Sleep Tips for Crossfit Athletes

1. Promotes muscle growth

Glucose is the primary form of fuel used by our cells to produce energy. When a glucose molecule enters the cell with the help of insulin, it will get incorporated into many metabolic cascades to produce Adenosine Tri-Phosphate (ATP).

During sleep, the process of transforming glucose into glycogen and storing it inside the liver and skeletal muscle begins. This will help the myocytes (i.e., muscle cells) become more efficient since the glucose (stored as glycogen) is readily available inside the muscle fibers.

If you are dealing with insomnia, the entire process of storing glycogen gets disrupted, which depletes the intramuscular storage of this crucial compound and negatively impacts your performance as a CrossFit athlete.

The primary hormone that mediates muscle repair is human growth hormone or HGH.

According toone study, the production of HGH is highly dependent on the circadian rhythm since the vast majority of the secretion occurs during sleep.

As a result, insomnia and other forms of sleep disorders lead to low levels of HGH, which negatively impacts your CrossFit training and muscle hypotrophy.

In a2017 cross-sectional study, scientists gathered hundreds of clinical data to analyze the relationship between sleep duration and quality with muscle growth.

At the end of the study, researchers found a clear connection between poor hypertrophy in participants who slept for less than 6 hours per day regardless of their efforts at the gym.

2. Promotes weight loss

Multiple research papers and clinical studies found a connection between poor sleep quality and obesity.

In a2008 meta-analysis, scientists showed that sleep-deprived individuals were more likely to gain weight and lose lean muscle mass (the last thing you want as a CrossFit athlete).

The review also demonstrated that 55% of adults and 89% of children who get less sleep than recommended had a higher body mass index (BMI).

Moreover, insomniac individuals reported numerous patterns of sleep disorders, such as binge-eating and frequent snacking. Researchers suggested that this phenomenon results from the feedback loop triggered by sleep on hunger hormones (e.g., ghrelin, leptin).

3. Maintains a healthy heart

According to the Centers for Disease Control and Prevention (CDC), people who sleep less than 7 hours a night are most likely to report having health problems, including cardiovascular disease.

This was attributed to the medical conditions that can get triggered by chronic sleep deprivation, which compose risk factors for heart disease themselves. These conditions include:

  • Blood hypertension
  • Type 2 diabetes
  • Obesity

In addition to optimizing heart health, sleep will also promote cardiovascular endurance, eventually, this leads to better performance at the gym and more muscle growth.

4. Optimizes the immune system

Healthy sleep helps in the regulation of inflammatory components (pro-inflammatory and anti-inflammatory compounds), helping athletes prevent annoying colds and infections that could potentially compromise their performance in different competitions.

Any disruption to this system leads to several complications, such as immunodeficiencies and recurrent infections.

In a 2013 study, researchers found that partial sleep restriction was associated with the excessive stimulation of inflammation signalling pathways that put patients at an increased risk of developing allergies, autoimmune diseases, and cardiometabolic diseases.

Sleep optimization for CrossFit athletes

Sleep for CrossFit athletes should become sacred since it plays an impactful role in their performance and gains during each workout routine.

For this reason, you need to learnhow to sleep for performance! By practicing certain activities, making lifestyle modifications, and consuming certain foods, you’ll be more likely to sleep for longer hours (7-8 hours of sleep) and experience several rapid eye movement (REM) cycles, which determine the quality of your sleep.

Train your circadian rhythm!

Now that you’ve become a mini-neuroscientist in the field of sleep, let’s see how you can train your circadian rhythm to optimize sleep quality:

Sunrise alarm clocks

As you know by now, light is the number one factor that determines when you sleep and when you wake up.
Sunrise Alarm Clock

For this reason, manufacturers developed a special type of alarm known as thesunrise alarm clock, which gradually increases the intensity of the light until it reaches a peak at the time you chose during the previous night.

This will create an artificial environment that mimics what our ancestors dealt with in the jungle (waking up because the sun is up). In fact, some devices shift colours fromred to orange to bright yellow, which is the order of colours seen during sunrise.

Sunrise alarm clocks will not only help you wake up in a peaceful and effective way, but it will also fine-tune your circadian rhythm to prevent sleep disorders. 

Wake-up light

Similar to sunrise alarm clocks, a wake-up light device starts glowing 30 minutes before the alarm goes off. However, this device can also producegradually increasing noises in association with the light.

The primary concept behind developing this device is to help you complete your REM cycle before waking you up. This way, you won’t have to deal with the startle, panic and grogginess that come with waking up in the middle of a REM cycle.

Natural exposure to light

Aside from the devices listed above, you could also go for a walk as soon as you wake up to regulate your circadian clock and set that time as the start of the day.

Avoid exercise before bedtime

As a CrossFit athlete, you may be tempted to do a couple of in-home training sessions to improve your performance and prepare for competitions. While that is great, you may want to avoid practicing any form of physical activity nearing your bedtime.

The reason is that exercising during the evening stimulates the production of hormones, such as epinephrine, norepinephrine, and cortisol.These hormones induce a state of alertness that renders sleep impossible.

Limit naps to 30 minutes

This one is straight forward.

Napping for long hours will mess up the circadian rhythm, which makes the brain believe that you no longer need to sleep even if it’s 2 A.M.

Therefore, try your best to limit your naps to 20-30 minutes to avoid advanced phase disorders. Another important tip is to nap for only one time a day. 

You can also check out and implement our 7 quick hacks for optimising you sleep!


The importance of nutrition for sleep optimization

The type of food you consume plays an important role in improving or worsening the quality of your sleep.

In this section, we will cover some basic foods and supplements that improve sleep for CrossFit athletes.

Collagen supplementation

Collagen is a commonly taken supplement in the field of fitness due to its muscle-promoting properties.

However, most people are unaware that collagen can improve sleep by aiding in the regulation of body temperature.

Here’s how it happens:

During the day, your core temperature varies slightly depending on the circadian rhythm. Most notably, the hypothalamus lowers your core body temperature near your bedtime to facilitate the process of falling asleep.

Once you fall asleep, the temperature decreases by approximately 0.5 Celsius.

Despite how insignificant this number may seem, researchers found that it is avital process to induce sleep.

One major substance that contributes to core temperature regulation is glycine, which is abundantly found in collagen.

In a2016 study, researchers showed that ingesting 3 grams of glycine (the typical quantity found in one collagen serving) helps individuals with different sleep disorders to:

  • Fall asleep faster
  • Maintain their sleep for longer hours
  • Optimize the quality of their sleep

B vitamins

According to scientists and sleep experts, sufficient amounts of vitamins B3, B5, B6, B9, and B12 may help people sleep better, as these vitamins regulate the levels of tryptophan, which is a precursor for melatonin. 

Interestingly,vitamin B12 regulates the circadian rhythm directly to help you maintain a consistent sleep schedule.


  • Seafood, poultry, and eggs.
  • Leafy greens, seeds.

Vitamin C 

Vitamin C is an important compound that mediates several biochemical cascades. This vitamin is uniquely obtained through dietary intake since the body cannot produce it.

In a2015 paper, vitamin C reduced the secretion of cortisol (primary stress hormone), which eventually improved sleep quality.


  • Lemon peel, pomegranates.
  • Cranberries, blueberries, and raspberries.


Studies found that taking magnesium supplements helps patients with insomnia to sleep better and increases the number of REM cycles.


  • Green leafy vegetables (e.g., spinach, kale).
  • Fruit (e.g., figs, avocado, banana, raspberries).
  • Nuts and seeds.


Turmeric is a traditional spice commonly used in Asia. For generations, people used this compound due to its potent anti-inflammatory and antioxidant properties.

Aside from tempering down inflammation and fighting off infections, turmeric alsoimproves sleep quality by regulating brain waves.


Ashwagandha is an ancient herb used for medicinal purposes. This herb offers numerous health benefits, including the reduction of cardiovascular risk and the optimization of sleep.

In a2019 randomized study, researchers concluded that taking 300 mg of Ashwagandha twice a day improves sleep quality and sleep onset latency.

While the exact mechanism that led to these results is still unclear,another study demonstrated the anxiolytic (i.e., anxiety-relieving) effects of Ashwagandha, which could explain it.

Sleep Tips for Crossfit Athletes 

Takeaway message

Sleep for CrossFit athletes is extremely important since it could optimise or hurt your performance in the gym. Therefore, you must learnhow to sleep for performance, which involves following all the tips listed above and adjusting your daily activities based on how well you sleep.

Hopefully, this article managed to shed some light on the importance of sleep optimisation for athletes, but if you still have any questions, please don’t hesitate to ask in the comment section below.

Yelana Jennings
Yelana Jennings

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