Since this marks the first full week of the new year, I'd like to discuss the cortisol awakening response (CAR). Understanding CAR is crucial because if it becomes dysregulated, it can make waking up in the morning and getting out of bed quite challenging, especially when you're trying to stick to your New Year's resolutions involving productivity or exercise. Properly regulating sleep to wake up at an optimal time and feel completely refreshed is essential for achieving your goals.
While most of you are familiar with the cortisol-melatonin diurnal cycle, it's still beneficial to briefly review it from a biochemical perspective to provide context. So, let's dive right in, starting with the retina.
The retina at the back of the eye contains various photoreceptor cells, including cones and rods responsible for vision. Additionally, there are specialized cells known as retinal ganglion cells (RGCs).
What sets RGCs apart is their pigment called melanopsin, sensitive to light but not involved in vision like cones and rods. Melanopsin enables RGCs to respond to changes in ambient light, particularly in terms of light intensity and timing.
When the eye is exposed to light, especially in the morning, melanopsin in RGCs absorbs light photons, setting off a series of biochemical reactions within RGCs. These reactions generate electrical signals or action potentials.
These electrical signals travel along the optic nerve to various brain regions, including the suprachiasmatic nucleus (SCN) in the hypothalamus. The SCN integrates signals from both eyes to assess light timing and intensity, helping it determine whether it's daytime.
In essence, these light signals from RGCs serve as vital cues for the SCN to align the body's internal clock with the external day-night cycle.
Within the SCN, these electrical signals initiate intracellular signaling pathways. One critical molecule in this process is CREB, a transcription factor. Once activated, CREB enters the nucleus of SCN neurons, binding to the promoter region of the corticotropin-releasing hormone (CRH) gene. This binding results in the transcription of CRH messenger RNA (mRNA) within SCN neurons.
The transcribed CRH mRNA is then translated into CRH protein within SCN neurons. Once synthesized, CRH is released from SCN neurons into the bloodstream.
CRH travels through the bloodstream to reach the anterior pituitary gland, where it binds to specific receptors on corticotroph cells. This binding activates signaling pathways leading to increased intracellular cyclic adenosine monophosphate (cAMP) levels.
This increase in cAMP levels within corticotroph cells stimulates the synthesis and release of adrenocorticotropic hormone (ACTH) from the pituitary. ACTH then leaves the brain and acts on the adrenal glands, promoting cortisol production. It's worth noting that cortisol is essential in the context of our discussion today.
In summary, this process involves the activation of retinal ganglion cells (RGCs) by morning light, triggering a complex signaling cascade within the SCN. This signaling ultimately leads to the transcription and translation of corticotropin-releasing hormone (CRH) within SCN neurons, culminating in the release of cortisol.
Now, what happens when there is no light? During the evening and nighttime, the retina detects the absence of light, leading to reduced stimulation of specialized RGCs containing melanopsin. With diminished light signals to the SCN, the SCN's activity changes.
In the presence of light, especially during the day, the SCN inhibits the pineal gland's melatonin production. However, in darkness, such as during the evening and nighttime, the SCN reduces its inhibitory signals to the pineal gland. This reduction allows the pineal gland to produce and release melatonin, signaling the body to prepare for sleep.
Now, let's explore the cortisol awakening response (CAR) and its connection to waking up feeling refreshed and ready to tackle the day. In general, cortisol levels peak shortly after waking up, known as the "cortisol awakening response." In the morning, cortisol promotes wakefulness and alertness, providing an energy boost to start the day. As the day progresses, cortisol levels gradually decline, reaching their lowest point late in the evening during sleep.
Aligning with our natural cortisol 24-hour cycle, it makes sense that low cortisol levels at night are crucial for promoting relaxation and facilitating the body's repair and regeneration processes during sleep.
Now, let's address the question of what happens when CAR becomes dysregulated, leading to either high or low CAR levels. Several studies have shown increased CARs in conditions such as relapsing-remitting multiple sclerosis, upper respiratory symptoms, visceral obesity, and metabolic syndrome. Conversely, decreased CARs were observed in patients with type 2 diabetes, chronic fatigue syndrome, hypertension, PTSD, and various mental disorders, as well as functional gastrointestinal disorders.
While there may be some overlap in symptoms between high and low CARs, it's well-established that a blunted or low Cortisol Awakening Response (CAR) significantly impacts one's ability to wake up with energy or even wake up on time, primarily contributing to chronic fatigue.
Before we delve into strategies to reset cortisol's diurnal rhythm, it's essential to rule out any underlying root causes like chronic inflammatory response syndrome (CIRS) aka mold illness... lyme... etc, parasites, or candida, as these can disrupt hormone regulation and lead to fatigue.
With that clarified, let's explore some tips and strategies to reset cortisol's diurnal rhythm:
1. Align your light exposure with the natural external environment. As the sun sets, start winding down and avoid artificial light. Consider using red light bulbs in the bedroom, as red light is more naturally present during sunset. You can also use blue light blockers when needed.
2. Expose yourself to bright light immediately upon waking to increase CAR.
3. Engage in physical activity early in the day, including high-intensity exercise, which has been shown to elevate CAR levels in healthy individuals. Ensure you're not overtraining, as that can also disrupt cortisol regulation.
4. Try cold therapy, like cold plunges, showers, or ice baths early in the day, which can stimulate cortisol production.
5. In the evening, avoid overstimulation by refraining from caffeine, intense exercise, loud noises, and alcohol before bedtime. These factors can disrupt your cortisol curve.
Now, let's explore strategies to support melatonin production, which, in turn, can help regulate cortisol's diurnal rhythm:
1. Include foods rich in melatonin or its precursors, like tryptophan and serotonin, in your diet. These can enhance sleep quality. Foods such as tart cherries, turkey, pistachios, and walnuts can be helpful.
2. A natural pineal peptide bioregulator called endoluten, which supports the pineal gland and promotes proper melatonin production. Although there's no direct correlation between endoluten and CAR in research studies to date, it can aid in achieving the desired melatonin increase at night which we know is essential for supporting the long-term goal of regulated cortisol-melatonin curves.
In conclusion, understanding the cortisol awakening response and its regulation is crucial for maintaining energy, waking up refreshed, and achieving your goals. By aligning your daily routines with the natural diurnal rhythm and addressing any potential disruptions, the cortisol awakening response should benefit greatly (leading to more productive mornings).
Source:
Powell DJ, Schlotz W. Daily life stress and the cortisol awakening response: testing the anticipation hypothesis. PLoS One. 2012;7(12):e52067. doi: 10.1371/journal.pone.0052067. Epub 2012 Dec 20. PMID: 23284871; PMCID: PMC3527370.
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