Stress is a natural and unavoidable part of life, manifesting in various forms, be it psychological challenges or environmental pressures such as the ongoing fear of job loss or looming assignment deadlines. Its impact can be positive and negative, influencing our physical and mental well-being. Numerous factors, including work, relationships, health, life events, and personal struggles, contribute to stress. While stress can serve as a motivator, helping us cope with challenges and overcome obstacles, it can also threaten our health when it becomes chronic or overwhelming.
One of the ways stress affects us is through the release of hormones in our bodies. These chemical messengers regulate diverse functions such as metabolism, immunity, the sleep-wake cycle, mood, and memory. This orchestrated hormonal response, often referred to as the "fight- or-flight" response, has evolved as a survival mechanism essential in confronting immediate threats. However, the modern lifestyle can trigger this response in non-life-threatening situations like traffic jams, work pressure, and family issues. While this heightened response was once necessary for survival, it may not be ideal when facing everyday stressors at home. In this blog post, we delve into our hormonal response system to stress, exploring essential stress hormones, their functions, and their effects, and consider supplements that may assist in managing various types of stress.
Understanding the Stress Response:
Stress hormones, essential for survival, can have adaptive and damaging effects on our health when their balance is disrupted. The stress response is a dynamic process aiding the body in immediate threat situations by increasing heart rate, blood pressure, breathing rate, and muscle tension. It also influences cognitive functions, mood, and memory. However, prolonged exposure to stress hormones can be detrimental. Stress, in its various forms, constantly challenges the body's homeostasis, a delicate balance maintained through internal feedback mechanisms.
The physiological impact of stress is termed the allostatic load, where the protective effects of stress hormones, in the short term, may lead to pathophysiological changes over time. The stress response initiates in the brain, where the amygdala signals the hypothalamus, triggering the autonomic nervous system. This system, which consists of the sympathetic and parasympathetic branches, coordinates the "fight-or-flight" and "rest and digest" reactions in order to preserve homeostasis. The sympathetic nervous system activates physiological changes, preparing the body for action, while the parasympathetic system promotes recovery.
Hormonal Cascade and the HPA Axis:
Following the initial stress response, the hypothalamus activates the hypothalamic-pituitary-adrenal (HPA) axis, a critical stress response system. The HPA axis releases hormones like corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH), releasing cortisol from the adrenal glands. Proper functioning of the HPA axis ensures a swift response to stress and a return to homeostasis. However, chronic stress can lead to allostatic overload, dysregulating the HPA axis and causing physiological detriment.
Components of the HPA Axis:
The HPA axis comprises the hypothalamus, pituitary gland, and adrenal glands, working synergistically to regulate energy, stress levels, metabolism, and immune responses. Dysregulation in any component can trigger a cascade effect, impacting other systems.
1. Hypothalamus – Located in the brain, initiates a stress response, connecting your nervous system with your hormones via the pituitary gland.
2. Pituitary gland – Also located in the brain. The pituitary gland receives the message and releases messenger hormones.
3. Adrenal glands – The messenger hormones from the pituitary travel to the adrenal glands, which sit atop the kidneys and release cortisol and adrenaline.
Chronic stress, common in modern life, can lead to persistent HPA axis activation. Increased cortisol levels typically cause a decrease in cortisol production, as this system functions on a negative feedback loop. Higher amounts of cortisol would trigger the negative feedback loop in a regulated response, thus lowering cortisol levels and deactivating the stress response. However, the constant demand for cortisol production may disrupt the negative feedback loop needed to turn off the system, and then elevated cortisol levels fail to reduce the stress response. Over time, this can result in structural and functional changes, affecting receptors and leading to HPA axis dysregulation. As no system operates in isolation, imbalances may extend to other physiological processes, compounding the impact of chronic stress on overall health.
Symptoms of high cortisol might be:
tired and wired
trouble sleeping
midnight waking
no energy in the morning
can’t fall asleep
belly fat
anxiety
short fuse
coffee cravings
hair loss
The Three Stages of HPA Axis Dysfunction:
Dysfunction within the Hypothalamic-Pituitary-Adrenal (HPA) axis is gradual, unfolding over months or even years. Three distinct stages characterize the progression of HPA axis dysregulation:
1. Alert Stage:
In the initial stage, the body responds to stress by releasing cortisol. This heightened alertness prepares us to face the perceived threat, resulting in elevated cortisol levels. This phase is characterized by increased vigilance and readiness to engage with the stressor.
2. Resistance Stage:
Extended exposure to chronic stress leads to a prolonged increase in cortisol levels. During the resistance stage, the adrenal glands struggle to meet the sustained demand for cortisol production. This phase is characterized by a challenging effort to maintain cortisol levels, ultimately resulting in lower-than-optimal cortisol levels.
3. Fatigue Stage:
As chronic stress persists, the adrenal glands reach a point of “exhaustion,” or reduced adrenal production of cortisol, making it difficult to maintain any cortisol levels. In the fatigue stage, cortisol levels plummet, further contributing to the development of HPA axis dysregulation that is caused by the adaptive changes initiated by the hypothalamus and pituitary. This phase is characterized by very low or even nonexistent cortisol levels.
While the three stages provide a general framework, individual experiences and responses to stress may vary. Identifying which HPA axis dysregulation stage requires a distinct understanding of personal stressors and their impact on the body's adaptive response system.
Symptoms of low cortisol might be:
severe fatigue
memory loss
frequent sickness
overreacting
crying spells
lack of motivation
lightheadedness
salt cravings
low libido
unstable blood sugar levels
Stress and hormones are such a large and complicated topic, we've divided it into two parts to be less overwhelming. Stay tuned - so much more to come in part 2!
Be well,
Natalie & Zeneve (dietetic intern)