The relationship between stress and skin health has been anecdotally documented for a long time. We knew that stress affected skin health - but the exact mechanisms were unclear.
In the last decade however, studies have finally painted a much clearer picture of how stress affects the skin. To understand the complex processes involved, we have to delve into multiple disciplines of human health, including psychology, endocrinology, immunology, and skin neurobiology.
So let's start by talking about stress itself.
When we refer to stress in this particular context, we are specifically referring to psychological stress.
Psychological stress arises when the individual perceives that the emotional/physical/mental pressure he/she is under, exceeds their adaptive power.
Our bodily response to this stress, is activation of the sympathetic nervous system, AKA: fight or flight mode.
But what actually happens during fight or flight?
Heart rate increases
Blood pressure increases
Pupils dilate
Breathing rate increases
Transportation of nutrients and oxygen to major muscle groups is accelerated
Pain response is compromised
Blood supply to the skin is reduced as blood is diverted to muscles
Functions that are not necessary for immediate survival are put on the back burner. This means digestion, tissue repair, reproductive and growth hormone production, are all temporarily halted.
Fight or flight is a carefully orchestrated sequence of hormonal and physiological responses, adapted to allow us to either fight off a threat or flee to safety. It's a survival response, and one that evolved to deal with life-threatening situations.
Unfortunately for us, our "fight or flight" response can also be activated by non-life-threatening situations - if we perceive them to be stressful enough. That includes: relationship stresses, traffic jams, work pressure, study/school stress, running late for a meeting - the list goes on.
Our bodies do not know the difference between day to day stresses and an attacking predator, and as a result, our stress response system can become chronically activated.
Let's dive a little deeper.
Our stress response begins in the brain. More specifically, a part of the brain called the amygdala.
The amygdala processes emotional responses, including fear, anxiety, and stress. It also processes visual and auditory information from the eyes and the ears. When it perceives a danger, it sends a distress signal to the hypothalamus.
The hypothalamus is located deep in the brain, just above the brain stem. It's essentially a control centre for the body, serving many functions including:
releasing hormones
controlling appetite
managing sexual behaviour
regulating emotional responses
regulating body temperature
When the hypothalamus receives a distress signal from the amygdala, it stimulates the pituitary gland (which sits below the hypothalamus) by releasing a hormone called CRH: Corticotrophin Releasing Hormone.
When activated by CRH, the pituitary gland releases a hormone called ACTH: Adrenocorticotrophic Hormone.
ACTH then stimulates the adrenal glands to secrete cortisol into the bloodstream, thus completing what is referred to as the HPA Axis (Hypothalamic-Pituitary-Adrenal Axis).
Now let's talk about cortisol.
Cortisol is a steroid hormone that plays several important regulatory roles in our bodies, including:
regulating our stress response.
regulating use of fats, proteins and carbohydrates
regulating metabolism
suppressing inflammation.
regulating blood pressure.
regulating blood sugar.
contributes to sleep-wake cycle.
We need a baseline level of cortisol for our body to function normally, and we produce it even when we are not stressed. Cortisol production in the body normally peaks when we first wake up, and then gradually declines over the day, in line with our circadian rhythm.
When we are under stress, we produce higher levels of cortisol - but the body's stress response system is usually self-limiting. Once the stress has passed, cortisol levels return to normal and de-prioritised systems resume their regular activities.
However if we are chronically stressed, and constantly activating our HPA Axis, the fight or flight response remains activated.
Long term activation of this stress response system, and constantly elevated levels of cortisol and other stress hormones, can put us at increased risk of a number of health issues.
So what happens when we have chronically high cortisol levels?
There are a number of undesirable effects from chronically high cortisol, including:
- fatigue
- anxiety
- irritability
- depression
- difficulty concentrating
- headaches
- high blood pressure
- weight gain
- sleep problems
- acne
- slowed healing
- digestive issues
It's important to note, stress is not the only possible cause of chronically high systemic cortisol. Other possible causes include:
- use of systemic corticosteroid hormones such as prednisone
- high levels of circulating oestrogen (eg. in PCOS, endometriosis, and during pregnancy).
Where does the skin tie in?
Remember the HPA axis we talked about just before? Well, the HPA Axis is not the only system of its kind in the body. We actually have a peripheral HPA axis in, you guessed it: our skin.
The skin contains homologues of every component of the HPA Axis, effectively allowing it to act as an endocrine organ in its own right.
Skin cells can produce cortisol, as well as 11B-HSD1 (11-beta hydroxysteroid dehydrogenase type 1), an enzyme that converts inactive cortisone into active cortisol.
Cortisol levels in the skin are directly correlated to systemic cortisol levels - in other words, when our body has high cortisol, our skin has high cortisol too.
Elevated cortisol in the epidermis of the skin have now been shown to cause a number of problems for skin health, including:
impairing permeability of the barrier by decreasing differentiation of keratinocytes
impairing immune function of the skin, thus increasing potential for infection
delaying wound healing
inhibiting proliferation of keratinocytes and fibroblast cells
increasing TEWL (transepidermal water loss) due to decreased barrier function
increasing sebum output and altering lipid composition of sebum causing increased viscosity, subsequently increasing congestion and breakouts
Put more simply, your skin will be more dehydrated, more congested, more breakout prone, more sensitive, slower to heal, and more susceptible to infection.
How can we benefit from this information?
Stress can be nearly impossible to avoid or control. For many of us, it's an inherent part of our lifestyle and feels unavoidable. So if we know that stress causes all of these issues but we cant get rid of the stress, why even learn about it?
Even though we can't totally resolve the root cause, explaining the why can be very comforting. Skin issues of unknown cause are far more frustrating and stressful and we can spend a lot of energy trying to work out what's going on. Not only that, but knowing stress could be the culprit will avoid incorrectly attributing changes in our skin to the wrong things.
With the understanding of what is going on in the skin when we're stressed, we can be more aware of potential changes to sensitivity, hydration levels, and wound healing. We will notice these changes faster, and can support our skin with additional hydration, and ease up on things that pressure the skin barrier, eg. exfoliation, AHA/BHA products, etc.
Understanding the extent of the detrimental effects chronic stress has on our skin, and our entire body, can also motivate us to be more mindful of managing our stress levels.
Ultimately this new research further strengthens the correlation between mental and physical health - not just of the skin, but the entire body - and highlights once again the importance of managing aspects of our health that we can't see, to benefit those we can.
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