Understanding hormonal health and the HPA axis
We often hear the words ‘hormonal health’ associated with the female reproductive system. However, hormones are in fact messengers within the endocrine system (the body’s hormonal system), which affect all genders (although some hormones have more specific roles within the male and female reproductive systems).
The endocrine system works closely with the nervous system and together they coordinate the regulation of all the body systems and functions (1), including metabolism, energy levels, and reproductive, cardiovascular and digestive systems.
Through a series of feedback mechanisms, hormones help to keep health in balance or in a state of homeostasis, and the reproductive system relies particularly on this intricate balance of hormones to function properly. Many factors can impact these feedback mechanisms which stimulate or suppress the production and release of hormones, and subsequently affect the function of the organs they are delivering messages to. Stress is one of the major factors affecting this. The HPA axis is an important mechanism central to stress responses and hormone balance. In particular, it affects stress hormones, and sex hormones (which relate to the reproductive system).
Stress is the term used to describe a “state of threatened homeostasis or disharmony” (2). This article will focus on stress and the HPA axis, and how this network creates changes to hormonal health through the interrelationship and dialogue between the nervous system, endocrine system, and reproductive system. This article will also offer advice on how to restore balance.
How do hormone health and the HPA axis work?
The HPA axis refers to a signalling system between three organs within the endocrine system: the hypothalamus, pituitary, and adrenal glands. The function of the HPA axis is to optimize performance according to circadian, environmental, and physiological demands (1). It is a natural response system of the body which allows us to adapt to stress by redirecting energy resources to meet real or anticipated demands (3).
The HPA axis is also an important mechanism in hormone health and balance. In response to the stimulus of stress, a cascade of hormonal messengers is released throughout the neuro-endocrine system which the HPA axis traverses. The production and release of steroid hormones are the end result of this cascade, but not the end of the response, which can continue through a series of negative feedback loops. Inappropriate or prolonged HPA axis activation is energetically costly, results in hormone imbalances, and if left unchecked is linked with numerous physiological and psychological disease states (3).
Cortisol is the main ‘stress hormone’ at the end of the cascade in the HPA axis, and it is released from the adrenal cortex into the bloodstream where it travels to effector sites in the body to carry out its function and make relevant physiological changes so that the body can deal effectively with the stress. This includes making more glucose available as an energy source to deal with the demands of stress and prepare the body for ‘fight or flight’ (4). Levels of cortisol circulating in the blood initiate negative feedback loops in the HPA axis, which can activate or suppress the further release of the hormones which then stimulate the release of more cortisol. In a healthy state levels of stress hormones are kept in balance through these negative feedback loops, and once the stress has passed the levels of cortisol will reduce, allowing a return to a state of homeostasis or healthy balance (5).
Adrenaline stimulates changes associated with this ‘stress response’ in the sympathetic branch of the autonomic nervous system. This activates the ‘fight or flight’ mode as blood is redirected from the organs to the skeletal muscles, heart rate increases and blood pressure rises, all preparing us physiologically to battle or run. In a healthy state it is natural to fluctuate between this sympathetic ‘fight and flight’ mode, and the parasympathetic ‘rest and digest’ mode of the autonomic nervous system.
Androgens are another hormone released by the adrenal glands as a result of HPA axis stimulation. These are termed male sex hormones because they contribute to the development of male features in men during puberty (5). They play less of a vital role in overall body functions compared to cortisol, but are important in the function of the reproductive system. In females they are a stimulus for libido, and when in excess androgens can contribute to the development of more masculine physical features, and cause disruptions in the female reproductive cycle.
Hormones which control the female reproductive cycle are also regulated by feedback loops between oestrogen levels, the hypothalamus, and the pituitary gland. Some of these hormones are also affected by the HPA axis, luteinising hormone (LH) secreted by the pituitary gland is one of them. The secretion of LH is stimulated by a decrease in oestrogen levels which naturally occurs during the first half of the menstrual cycle. This decrease in oestrogen levels is detected by the hypothalamus, which then sends gonadotropic-releasing hormone (GnRH) to the pituitary gland, which usually at the mid-cycle point prompts a surge in LH and oestrogen, as well as another hormone called follicle-stimulating hormone (FSH). It is this surge of LH and FSH together which initiates ovulation (6).
Stress and reproductive hormone health are closely linked when we consider that androgens are one of the end products of the HPA axis. Androgens are also converted to another sex hormone called oestrone. Increases in oestrone levels circulating in the blood stimulate excess production of LH, which can disrupt the natural hormone fluctuations in the female menstrual cycle and subsequently fertility (5). When LH levels are in excess this triggers the release of more androgens from the ovaries (6), and can result in something called androgen excess, which is often found in women with reproductive health issues such as polycystic ovarian syndrome (PCOS) and infertility.
The table below shows these hormones and their actions in the body.
|Name of hormone
|GnRH (gonadotropic-releasing hormone)
|Stimulates LH & FSH production in the pituitary gland
|CRH (corticotropin releasing hormone)
|Activates CRH receptors, stimulates ACTH release (7) in the pituitary gland
|Stress activates release of CRH
|CRH is the central regulator of the HPA axis (7)
|ACTH (adrenocorticotropic hormone)
|Regulates production of steroid hormones (cortisol and androgens) (8) in the ACTH receptors of the adrenal cortex
|LH (luteinising hormone)
|Triggers release of androgens from ovaries
|FSH (follicle stimulating hormone)
|Glucocorticoids (mainly cortisol)
|Stimulates the production of glucose (gluconeogenesis). Provides resistance to stress, dampens inflammation, depresses immune responses (5)
|Converted to oestrone* androgens have a masculinising effect in females (5)
|*rising levels of oestrone stimulates further production of LH
Understanding the root
Dysfunction of the stress response and HPA axis is extremely common nowadays (9). The fast-pace of modern life, and the pressure to be constantly doing or achieving something, creates a sense of mental stress for many people a lot of the time. We are almost always stimulated externally through television, social media, the news and other media during waking hours. Oftentimes they are used as a distraction from other stressors, or to ‘relax’, when in fact physiologically it is putting more stress on our nervous systems.
In addition to the everyday stressors of modern life which impact the HPA axis, the lifestyle accompanying this is far more sedentary than ever before. This has consequences, as exercise and movement is fundamental for managing stress and balancing hormones. In addition, the modern Western diet is typically far removed from a whole-food diet, often consisting of over-consumption of food, highly processed with many artificial ingredients, and an excess of refined carbohydrates. This type of diet is not only nutritionally deficient lacking the basic nutrients required for the body to repair and heal itself, but also presents additional stress on the body’s systems to process such food. This contributes to blood sugar highs and lows which in turn affect HPA axis function and hormone health (9).
There is a tendency within modern society to be living far from the natural rhythms of life which support our health and reduce the feeling of stress. These include being physically active, spending time outdoors in nature, being connected with a supportive community, and spending time with loved ones, all of which help to keep our body systems in greater harmony. The lack of this combined with the modern stressful lifestyle is a recipe for dysfunction of the HPA-axis and the systems it regulates, such as hormone health.
The circadian rhythm is one example. The circadian rhythm is linked to the day-night and waking-sleeping cycles, and it is partially governed by levels of cortisol, which naturally spike in the morning and drop at night, to ensure energy for daytime activity and a restful state for sleeping at night. This natural rhythm is intrinsically linked with the HPA axis. Lack of sleep is common in modern society, as sleep is often not prioritised over getting more done, meaning that our circadian rhythms become disrupted. Additionally, over-stimulation of the HPA axis (which can be triggered by lack of sleep or other causes), can lead to sleep problems due to disharmony in the natural variations of cortisol levels (9). This can have a knock-on effect causing imbalances in sex hormones and reproductive health.
Other factors affecting the HPA axis can include trauma of a physical nature (which can include accidents, injury, surgery, over-training or excessive exercise), and emotional trauma from stressful life events. Our perceptions of stress are also a big factor, which often come from the subconscious mind or unmanaged stress in the body. Whilst we may not consciously think we are stressed, we may be holding onto tension in our bodies or have aspects of our subconscious which mean we are more reactive to difficult situations (9).
Whatever the root source (which is likely to be from a combination of factors), prolonged activation of the stress response can lead to over-activation of the HPA axis which can mean that over time the body becomes less responsive to the effects of cortisol and the feedback loops stop working so well. This leads to constantly elevated levels of stress hormones and adrenaline (another hormone released from the adrenal gland as part of HPA axis stimulation) (5). This can often be accompanied by the feeling of being ‘tired and wired’ a lot of the time. If this continues there is eventually a deficiency in cortisol, and feeling exhausted. This is sometimes referred to as ‘adrenal fatigue’ or ‘burnout’.
As is made evident, hormonal balance is complex, and multifaceted. There are herbs which can help to rebalance reproductive hormones via the HPA axis, but it is essential that stress is managed holistically too. Herbal support can be provided to restore and nourish the adrenal glands, nervous and endocrine systems and improve the body’s resilience to stress.
Signs and symptoms
The list of symptoms may be very different from one person to another, but common symptoms include (9):
- Wake up tired, or feeling fatigued throughout the day
- Cognitive issues such as “brain fog”
- Trouble falling asleep
- Lower tolerance to stress, irritability, short temper
- Weight gain, especially in the midsection
- A weak immune system, getting sick more often
- Hair loss in women
- Low libido in men (80% of DHEA is produced by the adrenals and is involved in arousal)
There are many disorders associated with imbalances in the HPA axis and endocrine system. It is important to see a medical professional if you are struggling to manage stress or think you may have a medical condition.
Herbal solutions (except in acute conditions) usually work with the body’s natural healing potential, giving it a nudge towards working harmoniously. This means the body can function as it is designed to, within a healthy state of homeostasis. In the case of hormones and the HPA-axis, this is just what herbs are aiming to do, to give a nudge and ‘modulate’ rather than stimulate or suppress hormone levels.
Adaptogens: these are herbs which increase the body’s capacity to deal with stress. Adaptogens are usually given by herbalists because they seem to re-regulate disharmonies in the neuroendocrine and immune systems, helping to normalise and enhance their function (10). Adaptogens work well to regulate the HPA axis.
Ashwagandha is a tonic and calming adaptogen that enhances endocrine function, particularly in re-regulating the thyroid, testes and adrenals. It is effective for fatigue, and cloudy thinking, stress-induced insomnia, and nervous exhaustion (10).
Siberian ginseng is a mild adaptogen that strengthens the immune system, increases endurance and stamina, and speeds up recovery from excessive training. It can also help prevent immune depletion which is often caused by stress. It can enhance athletic performance, improve alertness and cognitive function when under severe stress or working long hours. It also helps to improve the quality of sleep and prevent night-time waking. It can rarely be over-stimulating for sensitive people (10).
Gotu kola is helpful for poor memory, anxiety, mental fatigue and irritability. Some evidence shows it can possibly prevent the increase of cortisol and adrenaline levels (10).
Rhodiola is cooling and so unlikely to cause over-stimulation, it is beneficial for the nervous system, helping to reduce fatigue, enhance alertness, and improve memory. It also helps balance blood sugar levels, enhance male and female reproductive function, and can help to relieve amenorrhoea and infertility caused by minor hormone imbalances (10). However due to its surge in popularity it is now an endangered species, and so one must be very careful when sourcing this medicine.
Shatavari is helpful for relieving minor hormonal imbalances that prevent pregnancy in women, and in cases of fatigue (10).
Reishi is a mild adaptogenic fungi with effects which are cumulative, including improving adrenocortical function and relieving stress (10).
Licorice is an adaptogen and adrenal tonic. Adrenal tonics help to improve the tone and function of the adrenal gland (11). Licorice benefits the HPA axis function, and helps to relieve symptoms of adrenal insufficiency such as fatigue, tiredness on waking in the morning, elevated cortisol and blood sugar levels (10). Adrenal tonics are particularly useful after prolonged periods of stress.
Blood sugar levels are closely linked to stress responses, and when we feel stressed or tired, we are more likely to let healthy eating habits slip. Eating a balanced diet will help to keep blood sugar levels balanced, maintain energy levels, and provide vital nutrients to allow sufficient energy production and healing to take place. Cinnamon is also useful for balancing blood sugar levels, as is going for a short walk after meals.
- Eat plenty of wholefoods (wholegrains, vegetables and fruit, pulses and legumes, nuts and seeds)
- Ensure you get enough protein (this is vital for most processes in the body, including repair and energy production). Things like meat, fish, eggs are ideal sources of protein.
- Eat less processed foods and refined carbohydrates (pre-packed / ready-made foods, foods with added white sugar)
Find out which things that trigger stress for you can be changed, and for those which can’t try to find strategies and other support which will help you to manage them. We all have different things that ground us and make us feel relaxed, from dancing to cooking. Make room for these nourishing activities so you can recalibrate and find balance consistently.
Learn to relax
This may sound obvious but in fact many of us have lost the art of relaxation, and feel we need to be doing something all the time. Relaxation can be deeply healing. Tension builds up in the body and must be removed for more ease. Consciously cultivating calm means when we do have inevitable stressful situations, our health and wellbeing are kept in good balance.
An example of a relaxation practise is Yoga Nidra, which is a form of guided relaxation referred to as ‘Yogic sleep’. In Yoga Nidra such relaxation can happen that one reaches the space between the waking and sleeping world, and the conscious and subconscious mind. This provides deep relaxation and helps to reset behaviours bringing more harmony into day-to-day life. This can be particularly helpful in altering our subconscious responses to stress.
Time in nature
Contact with nature is well established as reducing stress (12). Daily if possible!
Give time to pause, reflect, and calm the mind.
Our breath rate can be altered by HPA axis stimulation. For example, when one is stressed, our breath becomes shallow and only really goes as far down as the chest. This is when we are in the sympathetic or “fight or flight” state, and breathing this way is sure to activate that part of our nervous system. The opposite can also be true, and we can help to activate the parasympathetic (rest and digest) branch of the autonomic nervous system just by slowing our breath rate down so that the exhale becomes longer than the inhale.
Also, importantly when we breathe down into our bellies rather than chests this supports the shift into a more relaxed state. There are many techniques which can help with this such as 7:11 breathing, and also some pranayama practices from Yoga traditions such as deep breathing (Yogic breathing), anulom vilom and bhramari. These can all be helpful in slowing the breath rate down and resetting the autonomic nervous system.
- Spencer RL, Deak T. A users guide to HPA axis research. Physiology & Behavior. 2017;178(1):43-65. https://doi.org/10.1016/j.physbeh.2016.11.014.
- Guillams TG & Edwards L. Chronic Stress and the HPA Axis: Clinical Assessment and Therapeutic Considerations. The Standard. 2010;9(2). https://www.pointinstitute.org/wp-content/uploads/2012/10/standard_v_9.2_hpa_axis.pdf.
- Herman JP, McKlveen JM, Ghosal S, et al. Regulation of the Hypothalamic-Pituitary-Adrenocortical Stress Response. Compr Physiol. 2016;6(2):603-621. doi:10.1002/cphy.c150015.
- Fulford AJ & Harbuz MS. An introduction to the HPA axis. Techniques in the Behavioral and Neural Sciences. 2005;15(1);43-65. https://doi.org/10.1016/S0921-0709(05)80006-9.
- Tortora G & Derrickson B. Principles of Anatomy and Physiology. 13th Ed. Asia: John Wiley and Sons; 2011.
- Tricky R, Women, Hormones and the Menstrual Cycle. 2nd ed. Canberra, Australia: Griffin Press; 2003.
- Slominski A. On the role of the corticotropin-releasing hormone signalling system in the aetiology of inflammatory skin disorders. Br J Dermatol. 2009;160(2):229-232. doi:10.1111/j.1365-2133.2008.08958.x
- Allen MJ & Sharma S. Physiology, Adrenocorticotropic Hormone (ACTH) [Updated 2021 Aug 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500031/
- Patel D. HPA Axis Dysfunction Explained: The Facts You Need to Know. Functional Medicine. https://webfmd.com/hpa-axis-dysfunction/. Published 2019. Accessed October 09, 2022.
- Winston D, Maimes S. Adaptogens, Herbs for strength, Stamina, and Stress Relief. Rochester, Vermont.: Healing Arts Press; 2007.
- Bone K, Mills S. Principles And Practice Of Phytotherapy. China: Churchill Livingstone Elsevier; 2000.
- Hunter MC, Gillespie BW, Yu-Pu SC. Urban Nature Experiences Reduce Stress in the Context of Daily Life Based on Salivary Biomarkers. Frontiers in Psychology 10;2019. DOI=10.3389/fpsyg.2019.00722.