Sleep is a vital physiological process that occurs in most living organisms, including simpler life forms, such as single-cell organisms, which exhibited 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.
People who engage in high-intensity workout plans 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, 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.
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 as melatonin, 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 the suprachiasmatic 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.
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.
As you probably guessed, the mechanism of action of the circadian rhythm makes it susceptible to numerous issues, which leads to sleep disorders (e.g., insomnia).
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 experience shallow, fragmented, and poor sleep quality.
Moreover, studies found that a disrupted circadian rhythm increases the risk of obstructive sleep apnea, where the patient goes through repeated pauses of breathing during the night.
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:
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 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, the Diagnostic 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
The most common type of this disorder 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 occur at 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.
Obstructive sleep apnea (OSA) is commonly seen in a substantial number of people, manifesting as brief and repeated pauses in breathing during sleep.
The medical literature states that the duration of pauses must be at least 10 seconds to qualify for this definition.
The primary defect in OSA is the laryngeal 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.
According to the National 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 underdiagnosed, with some estimates stating that more than 80% of individuals with this condition have yet to be diagnosed.
Furthermore, people who engage in contact sports are more likely to develop OSA than the general population.
One of the main obstacles doctors come across when dealing with a sleep apnea patient is the difficulty of posing the diagnosis.
Today, the gold 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
Sleep optimization is crucial for several reasons, including muscle growth, performance, and energy production. Moreover, getting sufficient hours of sleep promotes better cardiovascular health and immune system function.
1. Sleep 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.
To get a more in-depth understanding of how this entire process works, we have to tackle the mechanisms by which muscles grow.
In a typical resistance training program, the workout gets divided into multiple exercises that you have to perform for an X number of sets.
Each set consists of 10-15 repetitions, which is the number of times you need to repeat the movement.
As you reach the final repetition of each set, you may experience what’s known as training to failure, which is a concept that focuses on exhausting your muscle fibres.
Consequently, the fibres will get torn (microscopically), requiring complex repair mechanisms that involve growth hormones and proinflammatory compounds.
The primary hormone that mediates muscle repair is human growth hormone or HGH.
According to one 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 training and muscle hypotrophy.
In a 2017 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. Sleep aids with weight loss
Scientists found repeated evidence of the relationship between poor sleep quality of weight gain.
In a 2008 study, researchers demonstrated that individuals who are sleep deprived were more likely to gain weight and lose lean muscle mass.
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, individuals with insomnia 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. Sleep promotes cardiovascular health
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 (e.g., blood hypertension, diabetes, obesity) for heart disease themselves.
In addition to optimizing heart health, sleep will also promote cardiovascular endurance and make each exercise more efficient. 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 you prevent annoying colds and infections.
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.
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.
For this reason, manufacturers developed a special type of alarm known as the sunrise 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 from red 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.
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.
Stay away from digital devices near your bedtime
Digital devices emit beams of UV light that suppress the production of melatonin. In other words, these devices create an artificial daytime environment to trick your biological hour into thinking that it’s not the proper time to sleep.
The National Sleep Foundation recommends avoiding the use of digital devices 2-3 hours before bedtime to optimize sleep duration and quality.
Related post Internet addiction
Don’t exercise before bedtime
Many people get tempted to do a couple of in-home training sessions before sleeping. 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.
Take short naps (20-30 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 only one time a day.
Don’t consume stimulants (e.g., caffeine, nicotine)
Sleep optimization requires you to cut any substance that may interfere with the function of the master clock. This means avoiding coffee, tea, nicotine-containing products (e.g., cigarettes), and of course, energy drinks.
You see, all of these products contain one or more nootropic agents (i.e., brain stimulant) that light up the brain and prevent you from falling asleep at the proper time.
You should also keep in mind that these products exert their action for long periods. In other words, if you drink a cup of coffee at 6 P.M. and your bedtime is at 10 P.M., the concentrations of caffeine will remain elevated in your blood, which could potentially cause acute insomnia.
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.
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 a vital process to induce sleep.
One major substance that contributes to core temperature regulation is glycine, which is abundantly found in collagen.
- Fall asleep faster
- Maintain their sleep for longer hours
- Optimize the quality of their sleep
Multiple research papers advocated for the use of B vitamins to improve sleep in people with insomnia. These vitamins regulate an important amino acid known as tryptophan, which gets used to produce melatonin.
Interestingly, vitamin B12 regulates the circadian rhythm directly to help you maintain a consistent sleep schedule.
- Cheese, milk, eggs, chicken, oysters, spinach, and kale.
Bananas are a rich source of tryptophan and potassium, which induce muscle relaxation and helps you fall asleep faster. A 2015 study found that potassium is important for muscle relaxation that occurs before sleep.
Another mineral found in bananas is magnesium, which has been proven repeatedly to aid patients with insomnia and other sleep disorders.
As we explained above, a low concentration of melatonin is often a trigger for insomnia; therefore, eating melatonin-rich foods can potentially improve the symptoms of sleep disorder.
The foods that have naturally-occurring melatonin include grapes, tomatoes, fish, eggs, and pistachios.
Passionflower tea contains large amounts of antioxidants that temper down inflammation and improve the function of the immune system. This herbal tea also exerts anxiolytic action (i.e., anxiety-relieving), which could potentially explain its positive effects on sleep.
Most of the effects seen with passionflower tea are attributed to a potent antioxidant known as apigenin, which induces calmness and relaxation by activating certain parts of your brain.
Passionflower also promotes the production of a neurotransmitter known as GABA. This chemical is the most effective anxiolytic agent in the brain.
As a result of these properties, passionflower is known to promote sleepiness, which can help you fall asleep faster and maintain it.
Sleep is a crucial physiological process to our health and should be given priority over everything else.
Hopefully, this article managed to shed some light on the importance of sleep optimization, but if you still have any questions, please don’t hesitate to ask in the comment section below.