Sleep
Mar 14, 2024
The Circadian Rhythm
Optimizing your biological rhythms enhances physical and mental performance.
Our health is suffering due to the misalignment of our illuminated lifestyle and hectic schedules with our inner clocks. This chronic disruption of our circadian rhythms is comparable to a traumatic brain injury. Achieving synchronicity in our circadian rhythms offers significant performance advantages and improves various aspects of our physiology.
What are Circadian Rhythms?
Circadian rhythms are biological processes that have evolved in response to daily light-dark cycles. Organisms, including humans, have adapted to thrive in their environment by synchronizing their internal time-management system, known as the Circadian Rhythm, with external cues. However, our modern environment lacks temporal coherence, with variable meal times, exposure to light at night, and flexible sleep patterns. This disrupts the robustness and self-sustainability of our biological clocks, preventing them from effectively tracking and predicting time and energy requirements.
Circadian Rhythm in Humans
Humans have inherited the selective advantage of time-sensitive biology, which has provided an edge for over 2.5 billion years. Maintaining internal and external coherence is crucial for our biological clocks. External cues known as zeitgebers, such as light, temperature, routine, food, and stress, influence our internal biology and help us stay in sync. However, our control over the environment, including artificial lighting and irregular meal schedules, has undermined the natural rhythms that our bodies have evolved to follow.
This disruption of our circadian rhythms has profound effects on our health. Reduction in natural light exposure, excessive caffeine consumption, sedentary lifestyles, irregular eating patterns, and late-night activities have pushed us out of sync with our natural biology. This erosion of our natural rhythms and zeitgebers contributes to metabolic problems, immune dysfunction, neurobehavioral abnormalities, and even increases the risk of certain cancers. Additionally, misaligned circadian rhythms are associated with accelerated aging and various neurological disorders such as Alzheimer's, schizophrenia, and bipolar depression.In order to promote optimal health and well-being, it is essential to prioritize the alignment of our circadian rhythms with our lifestyle and environmental factors. By establishing consistent routines, prioritizing natural light exposure, maintaining regular sleep patterns, and adopting healthy lifestyle habits, we can support the synchronization of our circadian rhythms and mitigate the adverse effects of circadian disruption.
Is our circadian rhythm in our brain or in our cells?
The circadian rhythm, which regulates our biological processes, is primarily controlled by the suprachiasmatic nucleus (SCN) located within the hypothalamus of the brain. This region serves as the "master" clock and consists of approximately 20,000 neurons.
The SCN receives information about external light conditions directly from the retina, making it highly sensitive to light. Light exposure can either advance or delay the signals generated by the SCN, effectively synchronizing our genetic, biochemical, and behavioral rhythms with the natural dark-light cycle. The neurons within the SCN maintain a regular pace and interact with neighboring neurons, creating a robust and self-sustaining rhythm that impacts both gene expression and brain activity.
Neurons from the SCN project into various hypothalamic nuclei that are involved in regulating sleep, wakefulness, body temperature, and appetite. This intricate network of connections allows the SCN to impose a regular schedule of activity and influence the rhythmic release of neurotransmitters, hormones, and glucocorticoids, such as cortisol.
Circadian Rhythm Disorder
Disruption of the circadian rhythm can lead to a wide range of symptoms that affect various systems in the body. These symptoms can escalate and potentially lead to the development of diseases if left unresolved. Some of the common areas where symptoms may manifest include reproductive issues, hormonal imbalances, compromised immune function, increased cancer risk, metabolic and energy management problems, adrenal issues, and neuropsychiatric symptoms.
How do you know if you have a circadian rhythm disorder?
Identifying whether you have a circadian rhythm disorder can be challenging, but there are early signs that may indicate its disruption. If you experience consistent difficulty falling asleep, staying asleep, or both, it could be a sign of circadian rhythm disruption. Nonrestorative sleep, where you still feel tired even after getting enough sleep, is another potential indicator. Daytime sleepiness or sleepiness during shift work, along with feelings of fatigue, exhaustion, and lethargy, may also point to a disrupted circadian rhythm.
Impaired productivity and performance, decreased alertness and difficulty concentrating, reduced psychomotor coordination, impaired judgment, and trouble controlling mood or emotions are additional signs to watch out for. You may also experience irregular aches and pains, including headaches, as well as stomach problems or digestive issues. It's important to note that these symptoms can also be present in other conditions or may have different underlying causes, so proper diagnosis is crucial.
Your Circadian Rhythm may even regulate gene expression.
The circadian rhythm has a profound impact on gene expression, influencing a complex network of genes and proteins that interact in a time-sensitive manner. Through interlocked transcriptional-translational feedback loops (TTFLs), these genes and proteins coordinate biology and behavior with the external environment. The suprachiasmatic nucleus (SCN), along with peripheral clock genes, plays a crucial role in creating temporal harmony within the body.
Recent micro-DNA analysis has revealed that circadian disruption can lead to global disturbances in genetic pathways, particularly in the liver, which controls important processes such as glucose and lipid metabolism. Studies that involve mutating or deleting clock components consistently support the view that normal clock function is essential for overall well-being.
It is now known that cells and tissues possess their own internal timekeeping ability, and the relationship between the SCN and peripheral clocks is bidirectional. The SCN, as the master clock, synchronizes with peripheral clocks to ensure coordinated functioning of the entire system. This federation of timekeepers collectively agrees on the "right" time for various functions, and the SCN exerts its standard rhythm when zeitgebers (external time cues) are missing or conflicting. This understanding opens up possibilities for resynchronization and retraining of the entire system by providing specific zeitgebers.
Local tissue clocks play a crucial role in controlling the expression of specific genes. Regulatory pathways related to survival, such as glucose management, are tightly controlled in a time-dependent manner to ensure coordination with other organs like the liver, muscle, and adipose tissue. The basic SCN rhythm is reinforced by hormonal patterns, particularly melatonin and cortisol, which contribute, complement, and consolidate the circadian cycles. Disruptions in cortisol or melatonin levels, often associated with stress and insomnia, can exacerbate irregularities in the circadian rhythm, leading to worsening problems until the cycle is interrupted.Overall, the circadian rhythm operates at a molecular-genetic level and involves intricate interactions between the SCN, peripheral clocks, and hormonal patterns to maintain optimal functioning and coordination within the body.
Wakefulness & Daily Cycles
The circadian rhythm plays a crucial role in regulating various biological processes, driven by the presence or absence of daylight. During the daytime, cortisol and other hormones promote alertness and keep us awake. As light levels decrease, the reduction in stimulation from the suprachiasmatic nucleus (SCN) triggers the production of melatonin, signaling the body to sleep. This synchronization of sleep-wake cycles with day and night promotes restorative rest and optimizes daytime activity.
'Internal Clock' Controlled Processes
While wakefulness is the primary cycle controlled by the SCN, it is now known that many other circadian oscillations affect our physiology. Numerous processes in our bodies exhibit daily rhythms, including blood glucose management, metabolism, inflammation, immune function, mood, memory, DNA repair, and neuroregeneration.
The significance of these clock-controlled processes highlights why disruptions to our circadian rhythm can have detrimental effects on health. Here are some key biological processes under rhythmic control:
Expression of detoxification enzymes to counteract free radicals.
Defense mechanisms against oxidative stress in red blood cells.
Lipolysis and the release of free fatty acids from white adipose tissue.
Endocrine clock genes that regulate lipolysis, adipogenesis, and energy conversion.
Genes involved in immune response and metabolic processes.
Thermoregulated lipolysis in brown adipose tissue to generate heat.
Regulation of glucose levels, uptake of free fatty acids, and clearance of serum lipids.
Circadian influence on insulin and glucagon levels, independent of feeding.
Functional circadian clock in the pancreas controlling insulin secretion.
Rhythmic abundance and decline of certain fecal bacteria in the gut.Oscillations in gastrointestinal activity and nutrient absorption.
Renewal of skin and gut epithelial cells.
Control of serum calcium levels and bone formation by vitamin D.
Daily fluctuations in the activity of liver enzymes (10% of liver genes exhibit rhythmic expression).
Genes associated with the metabolism of carbohydrates, lipids, amino acids, and bile.
Daily oscillations in NAD+ levels, which is utilized by SIRT1 to deacetylate clock-related proteins.
These examples demonstrate the wide-ranging impact of the circadian rhythm on our physiology and emphasize the importance of maintaining a well-aligned circadian system for overall health and well-being.
Can You Choose Your Chronotype?
The debate surrounding chronotypes raises questions about whether our inclination to be early or late risers is genetically predetermined or influenced by our actions and environmental factors. Are certain individuals more attuned to environmental cues or better able to adapt without predictable signals?
Considering the health benefits associated with chronotype, it suggests that we should actively shape our temporal destiny and seek zeitgebers that realign us with natural time. Establishing an efficient, entrained, and resonant circadian rhythm can enhance mental and physical performance, providing an energetic advantage for individuals ranging from athletes to entrepreneurs.
Circadian Chronotypes
Chronotypes help categorize individuals based on their patterns of activity and alertness during the day and night. Early types (E-types) tend to wake up and fall asleep earlier, while late types (L-types) have a preference for later waking and sleeping times. E-types and L-types often have distinct social schedules, and extreme cases can result in E-types waking up when L-types are going to sleep. L-types may experience more difficulties with social jet lag, the misalignment between internal and external time due to social obligations.
Chronotype assessment can be done through self-reporting questionnaires, including tools like the floating Circadian Rhythm Test button on this page. However, the accuracy of these assessments relies on memory and estimation of how one would respond to different mental and physical tasks.
Alternatively, studies employing Ambulatory Circadian Monitoring (ACM) sensors gather real-time data on environmental light and temperature exposure, wrist temperature, body position, and activity in free-living conditions. This extensive dataset helps classify individuals' chronotypes. Typically, around 60% fall into the middle category with no strong preference, while approximately 20% are early-types and another 20% are late-types.
Benefits of Chronotype Alignment
Circadian-controlled genes play a vital role in all of your essential biological functions. Even small improvements in efficiency can have a significant impact. When your entire system resonates in harmony with your schedule, you can expect the following benefits:
Consistent and rejuvenating sleep.
Optimal production of digestive enzymes and bile for efficient digestion.
Regulation of hormones, including ovulation in females.
Increased energy production.
Enhanced detoxification and improved liver function.
Efficient digestion and nutrient absorption.
Reduced oxidative stress and improved blood oxygenation.
Enhanced immune function and cellular rejuvenation.
Improved mental clarity and consolidation of memory.
Enhanced cellular cycling, including growth, repair, or apoptosis.
Better heart function and reduced risk of heart disease.
Reduced levels of stress and improved mood balance.
Improved glucose control and balanced appetite.
Reduced risk of DNA damage and cancer.
Optimization of hormone release at peak times, such as waking up.
Efficient thermoregulation for maintaining optimal body temperature.
By improving your Circadian Rhythm, you enhance the overall efficiency of your body. An efficient body has surplus energy to support cognitive function, repair processes, eliminate toxins, and operate at peak performance.
Establishing optimized circadian rhythms aligned with your daily routine enables you to schedule critical tasks during peak performance periods in your day.
What regulates your circadian rhythm
It is possible to establish a healthy and efficient circadian resonance with the natural environment or optimize your lifestyle, such as in shift work. By modifying your personal zeitgebers, you can achieve a more efficient oscillation of gene expression.
To optimize your genetic expression, careful analysis of shifts in energy, glucose, sleep, and subjective well-being is necessary.
Zeitgebers give you control over your genes, allowing you to adjust their operation to suit your lifestyle. Gathering the right data will help you determine what optimizes your rhythm.
Here are some key factors to consider:
Light
Expose your eyes to natural sunlight early in the day to mark your subjective dawn.
Limit light exposure before bed to create a subjective dusk.
Avoid exposure to stimulating short wavelengths of light at night.
Sleep
Reduce light after natural dusk and limit blue light to promote melatonin production.
Avoid eating and vigorous exercise for at least 2 hours before bedtime.
Engage in relaxing activities to wind down before bed.
Establish a bedtime ritual to enhance entrainment.
Create a sleep-friendly environment with appropriate temperature and reduced electromagnetic radiation.
Stimulants, Supplements, and Smells
Avoid consuming caffeine-containing substances and stimulants after midday.
Consider supplementation with magnesium, zinc, or melatonin, but use caution with melatonin.
Utilize herbs and essential oils, like lavender, to aid in sleep.
Temperature:
Take advantage of temperature variations throughout the day to reset your rhythms, such as using a hot shower or cold water immersion.
Diet
Pay attention to the type, timing, and portion size of your food intake.
Avoid late-night snacking and aim for lighter evening meals.
Stress
Reduce stress through exercise, relaxation techniques, and minimizing exposure to stressful stimuli.
Activity
Engage in exercise, social interaction, and feeding during the active phase of the day.
Plan exercise at different times of the day based on your goals and preferences.
Routine
Establish consistency in your daily schedule and compensate for changes in sleep due to travel or personal behaviors.
Utilize awareness of your rhythm and performance data to optimize your temporal alignment.
By implementing these strategies and personalizing them according to your needs, you can enhance your circadian rhythm and achieve peak performance points throughout your day.
Circadian Synchronicity
A mere 10 days of aligning your circadian rhythms can lead to improved insulin sensitivity, decreased blood glucose, cortisol levels, and blood pressure.
Imagine if you had a watch that consistently ran late. Would you consider it an "L-type" watch? What if the watch started dimming, had poor battery life, and became slower with each passing day? Would you see these as features or signs of a problematic watch? Clearly, it would be recognized as having a problem.
In the field of science, there is a tendency to study states of maladaptation rather than optimized adaptation. Insulin resistance is a maladaptive response to the food consumed and toxins inflaming the pancreas. Burnout is a maladaptation to excessive stress and the inability to reduce cortisol levels. Late-type chronotypes are maladapted to a healthy life in our modern environment. However, by resetting our timing and using the language of zeitgebers, we can rewrite our schedule.
The crucial aspect of circadian rhythms is their resonance or match with the environment, rather than simply adhering to a fixed 24-hour schedule. The "free-running period" is what happens to our internal clocks when they are not working in sync.
While there are limited animal studies tracking the benefits of establishing resonance between physiological and behavioral clocks, human studies are now emerging. We can embark on this journey together.
The potential for enhanced performance by adding just a little more energy and efficiency is immense. The personal gains in mood and stress reduction make it worthwhile to invest effort into this experiment.
Micro-DNA analysis and qualitative assays have identified an "ideal time" for the average human under ideal conditions. Although such ideal conditions are rare, it serves as a starting point when considering our daily schedule. Are you optimizing your day in alignment with your body?
How to determine your circadian rhythm:
Assessing Your Circadian RhythmWhile we may not have control over the timing of sunrise and sunset, we can pay attention to the signals we give our bodies and become better at meeting our own needs. Your SCN, along with organs, cells, and DNA, collaborates to establish a schedule that works for you. By increasing your body awareness, you can train that schedule to align with your life and make it more efficient.
Tracking Your Circadian Rhythm with BasisFor a more precise and daily system to monitor your circadian rhythms, you can utilize Basis. By using sleep and activity data from your wearables, Basis continuously interprets your circadian rhythm and provides guidance on how to improve your lifestyle habits. This helps you synchronize with your circadian rhythm, enhancing your overall health.
