Cortisol – the Essential Stress (Sleep) Hormone in Today’s Lifestyle
Here, in this article, let us take a look at the hormone “Cortisol.” Let us educate you in detail on how the hormone works and how it is used by the body. Also, what effects arise when you experience a lack of sleep?
What does cortisol do?
Cortisol hormone is one of the essential hormones in the human body. It is accountable for the innate alarm system that works at the time of stress or fear. When you experience a perceived threat or such situations, the hormone comes to your rescue and starts performing its functions. It acts as your body’s main stress or steroid hormone.
The hormone is produced at the outer cortex region of the adrenal glands located at the top of the kidneys. The triangular-shaped adrenal glands produce cortisol in response to pituitary or hypothalamus stimulation.
Balancing the cortisol secretion in your body does not only regulate your mood switches during flight and fight but also enables your body to gain good health.
As one of the glucocorticoids, this hormone power plays and balances the stress and related metabolisms in your body.
How is Cortisol Produced?
The cortisol production depends on the HPA axis in your body. The HPA axis refers to the interconnection of three regions: the hypothalamus, pituitary, and adrenal glands. The hypothalamus and pituitary work together with the adrenal gland to make the HPA axis and regulate cortisol release in the body.
During stress or lack of sleep, your body might have low cortisol levels in the bloodstream. The hypothalamus region detects these lower cortisol levels in the bloodstream and produces CRH (corticotropin-releasing hormone).
When the pituitary gland’s cells sense the CRH hormone, it releases ACTH (adrenocorticotropic hormone) in return. This ACTH reaches the bloodstream and gets transported throughout the body. When the adrenal gland cells detect this ACTH, it releases cortisol into the bloodstream to compensate for the lower levels.
Once the cortisol levels in the blood become higher, a negative feedback mechanism initiates. This hinders the hypothalamus from producing CRH and the pituitary gland to produce ACTH.
More often than not, you can observe higher levels of cortisol after complete sleep (during the morning). These levels get dropped throughout the day at a slower pace. This cycle refers to the diurnal rhythm
How does your body use Cortisol?
More than a stress hormone, cortisol influences a lot of other functions of your body. The function depends on the presence of cortisol receptors in the cells. Regardless, almost all the cells all over the body tend to contain cortisol receptors.
The primary functions and benefits of cortisol include:
- Regulation of the blood sugar and pressure levels
- Regulation of various body metabolisms by controlling the consumption of carbohydrates, fats, and proteins
- Acts as the central alert system and handles the primary functions of fight and flight
- Reduction in inflammations
- Helps in memory formation by brain cells
- Control of your sleep-wake cycle
- Balancing the salt and water content in the bloodstream
- Helps in the fetus development for pregnant women
- Manages stress and restores energy balance
What are the symptoms of cortisol level imbalance?
Higher Levels of Cortisol (Hypercortisolism)
Cortisol level increases at the time of stress or any fearful event. But, in the absence of such stress, your body’s cortisol level should be reduced. Only then the body’s normal functions: Digestion, Growth, and Immunity will get back to normal.
What happens if the cortisol levels still get elevated instead of reducing? It causes unwanted health problems, including:
- Weight gain around the abdomen, chest, and face
- Slender arms and legs
- Osteoporosis (weak or brittle bones)
- Prolonged anxiety, mood switches, and depression
- Increased fragility of skin tissues (slow healing in the case of inflammations or acne)
- Increased frequency of urination
- Irregular menstrual periods and growth of facial hair for women
- Memory and concentration problems
- Sleep fragmentation or other sleeping disorders
- Pulmonary or CNS related problems
- Imbalanced blood pressure and sugar levels
- Increased thirst throughout the day
- Libido (Lack of sex drive)
Lower Levels of Cortisol (Hypocortisolism)
Lower cortisol levels occur due to improper secretion of cortisol by the adrenal gland. This condition refers to primary adrenal insufficiency.
Your body communicates to you over time in the case of consistent lower cortisol levels in the bloodstream. They include:
- Darkened skin on scars and skin folds
- Loss of weight
- Lower blood pressure
- Increased muscle weakness
- Constant abdominal pain
- Feeling tired throughout the day
- Daytime fatigue or Dizziness
- Diarrhea, nausea, and vomiting
- Loss of appetite
How is the lack of sleep and Cortisol related?
Centuries before, a human body identified the lack of sleep as a stressful or alarming situation. But, in recent times, lack of sleep is not a one-time signal to the human body. People are wide awake in their nocturnal sleep time, affecting the cortisol, i.e., HPA axis functioning at a greater level.
So far, many studies have proven the significant association of sleep deprivation from sleep disorders and abnormal cortisol levels in the serum. Research also shows the inverse relation of sleep and the HPA axis.
Normal Sleep-Wake Cycle and the Circadian Rhythm
A human’s sleep architecture characterizes stages of the sleep cycle as follows:
- Stage 1: This stage of the sleep cycle accounts for the transition between wakefulness and sleep. Occurring for about 5-10 minutes, this stage mixes up theta waves, slow eye movement, and chin electromyography (EMG).
- Stage 2: Sleep spindles initiate and last for about 20 minutes. In this stage, both the body temperature and the heart rate decreases.
Deeper Slow-Wave Sleep
- Stage 3: This stage of sleep cycle accounts for the transition between light sleep and deep slow-wave sleep. The stage also characterizes 20-50% of delta waves.
- Stage 4: This stage characterizes more than 50% of delta waves and is often referred to as Delta sleep. This lasts for about 30 minutes.
REM (Rapid Eye Movement) Sleep
- Stage 5: This stage makes up a mix of theta waves, rapid eye movements, and increased respiration rate. Only chin electromyography (EMG) seems absent. This stage lasts for about 90 minutes.
As a cycle, the sleep starts sequentially proceeding with stages 1, 2, 3, and 4. After stage 4, stages 2, 3, and 4 get iterated before stage 5 commences, constituting a non-sequence flow. But, after stage 5, the body returns to stage 2. This cycle repeats, with REM lasting longer with each cycle.
Cortisol secretion happens in a waveform like the sleep cycle and repeats every 24 hours. This pattern refers to the circadian rhythm. The pattern follows a low cortisol level (nadir) at midnight and tends to increase after the onset of deep sleep. This increase in cortisol levels reaches a maximum in the morning at about 9 am.
As the day progresses, the cortisol levels start with a progressive decrease. This cycle repeats every day, and your body allows your body to secrete cortisol at various amplitudes throughout the cycles.
- Low levels of cortisol in the evening or night link to MR binding (Cortisol and mineralocorticoid receptor binding).
- High levels of cortisol in the morning link to GR binding (Cortisol and glucocorticoid receptor binding).
Sleep Deprivation and Cortisol Rhythm
In stressful times (lack of sleep), GRs get activated, thus increasing the HPA activity leading to elevated CRH production. This causes elevated cortisol levels in the bloodstream and increases the light sleep. This, in turn, results in frequent waking.
For sleep to occur, HPA axis activity has to be at its lowest. In this case, the MR binding of cortisol has to happen. Rather, if HPA axis hyperactivity occurs, it leads to fragmented/shortened/slow-wave sleep.
Various Sleep Disorders caused by Cortisol Levels
How can insomnia affect cortisol levels
Insomniac patients with a high degree of sleep disturbance (% of sleep time < 70) show higher levels of cortisol. In contrast, a low degree of sleep disturbance experiencing Insomnia patients showed low levels of cortisol. This case of sleep disorders follows the usual circadian cycle.
The increase in cortisol may result from increased CRH activity and CNS norepinephrine. Apart from activating pituitary ACTH, CRH also activates locus coeruleus (LC). The LC uses norepinephrine and further stimulates the paraventricular nucleus, which serves as an important control center in the brain for several homeostatic responses within your body. This can account for the elevated release of CRH.
The symptoms of insomnia include difficulty paying attention, hard to fall asleep, fragmented sleep, sudden awakes, restless feeling, daytime sleepiness, poor concentration, and the frequent possibility of accidents.
How can Sleep Apnea affect cortisol levels?
This sleeping disorder is associated with nocturnal hypoxia, excessive daytime sleepiness, or nocturnal sleep fragmentation. Research studies prove the elevated levels of cortisol in sleep apnea patients. Much like insomnia if not properly treated the elevated levels of cortisol within the body can wreak havoc on your body’s ability to stay in homeostasis and live a healthy life.
Sleep apnea symptoms include headaches, hyperactivity in kids, feeling crampy, drowsiness, lack of sex drive, depression, and swelling of legs.
Cushing’s syndrome may arise due to increased cortisol production by the adrenal gland’s tumor cells or the pituitary gland’s tumor cells (ACTH-inducing cortisol production). This condition leads to increased weight gain, hypertension, diabetes, blurred vision, skin tissue breaking, female baldness, and muscle weakness.
Non-cancerous tumor cells, called adrenal adenomas, cause increased cortisol production. However, these tumor cells occupy the least reason to cause Cushing’s syndrome.
Evidence shows the association of sleep disorders with the frequency of sleep apnea. Mild sleep apnea and significant or severe apnea constitute these types of Cushing’s syndrome. Those with mild or severe sleep apnea showed increased sleep fragmentation and decreased delta (deep sleep).
Lower cortisol levels owing to adrenal insufficiency can account for this disease. Though the symptoms may show up at a gradual pace, the consequences and the ill effects may cause serious health concerns, requiring immediate consultation with a Doctor. Some of the symptoms include abdominal pain, salt craving, daytime fatigue, vomiting, decreased appetite, and hair loss.
The two adrenal insufficiency types include: Primary and Secondary. Primary adrenal insufficiency arises due to damaged cortex tissue of the adrenal glands. Whereas, the secondary adrenal insufficiency arises due to lower ACTH production, leading to decreased cortisol production.
Patients with adrenal insufficiency during nocturnal sleep showed decreased REM sleep and increased sleep fragmentation. Research studies prove the need for adequate levels of cortisol in retaining prolonged REM sleep.
Others Physiological Problems
- Increased glucocorticoids (cortisol) increase blood glucose (sugar levels) and decreases adiponectin levels. Thus, sleep deprivation with dysfunctional HPA axis activity (Cortisol imbalance) also leads to neuroendocrine dysregulation.
- Cortisol increases blood pressure during flight and fight. But, this increased blood pressure cannot stay longer, even after stressful situations. When this continues, arterial constriction does not change, causing damage to blood vessels. This paves the way for severe heart attacks in some cases.
- Elevated cortisol levels sometimes hinder optimal sexual hormone production. Over time, this leads to the disruption of menstrual or ovulation cycles.
- Though cortisol seems to reduce inflammations, at higher levels, it may suppress the immune system. This leads to increased susceptibility to colds and fever.
- When the cortisol levels get elevated, the other function of the body (Digestion) gets suppressed. When indigestion happens continuously, the mucous layer of the stomach gets damaged, leading to inflammation. This further increases cortisol production.