Perimenopause and Cortisol: Understanding the HPA Axis and Managing Stress Hormones
Cortisol dysregulation is common in perimenopause. Learn what the evidence says about stress hormones, practical interventions, and when to seek specialist help.
The HPA Axis in Perimenopause
The hypothalamic-pituitary-adrenal (HPA) axis is the body's central stress-response system. When you encounter a stressor, the hypothalamus signals the pituitary, which signals the adrenal glands (two small glands that sit above your kidneys) to release cortisol. Cortisol raises blood glucose, sharpens alertness, and mobilises energy. It is an essential hormone when used appropriately, but problems arise when the system is chronically activated without adequate recovery. Estrogen and progesterone both modulate HPA axis activity. Estrogen has a stimulating effect at the hypothalamus, while progesterone, particularly via its metabolite allopregnanolone, has a calming, GABA-like effect on the nervous system. As both hormones fluctuate and decline in perimenopause, HPA axis regulation becomes less stable. Many women notice increased reactivity to stress, worsened anxiety, disrupted sleep, and difficulty returning to calm after stressful events. These are HPA axis changes in action.
What 'Adrenal Fatigue' Gets Right (and Wrong)
The term 'adrenal fatigue' is widely used in wellness spaces to describe a cluster of symptoms including persistent fatigue, low motivation, trouble getting going in the morning, and difficulty handling stress. However, it is not a recognised medical diagnosis. True adrenal insufficiency (Addison's disease and secondary adrenal insufficiency) is a serious condition with specific clinical features and a clear diagnostic pathway, and it is rare. The symptoms attributed to 'adrenal fatigue' are real, but they reflect HPA axis dysregulation, cortisol rhythm disruption, and the compounding effects of perimenopause, poor sleep, and chronic low-grade stress rather than adrenal glands that are genuinely exhausted. Understanding this distinction matters because the solutions differ. Chasing a wellness label can lead to unnecessary supplements and spending, while addressing the underlying drivers of HPA dysfunction (sleep, stress, nutrition, movement) has a strong evidence base.
Cortisol Rhythm and Why It Matters
Cortisol follows a daily pattern called the cortisol awakening response (CAR). It peaks sharply within 30 to 45 minutes of waking, providing the alerting signal that helps you get up, think clearly, and engage with the day. It then declines across the day, reaching its lowest point in the early hours of the night. When this rhythm is disrupted, problems emerge: low morning cortisol produces persistent fatigue and foggy mornings, while elevated evening cortisol prevents sleep onset and contributes to the racing thoughts and wakefulness many perimenopausal women experience at night. Night sweats and hot flashes further disturb sleep, feeding back into cortisol dysregulation and creating a cycle that is hard to break without deliberate intervention. Cortisol rhythm disruption also feeds into insulin resistance, immune dysregulation, and low mood, so addressing it has benefits across multiple systems.
Evidence-Based Interventions
Sleep is the most powerful single lever for HPA axis recovery. Prioritising consistent sleep and wake times, keeping the bedroom cool and dark, and addressing hot flashes with appropriate treatment (including HRT where indicated) directly improves cortisol rhythm. Mindfulness-Based Stress Reduction (MBSR) has a strong randomised controlled trial evidence base for lowering cortisol levels and improving self-reported stress. Even a brief daily mindfulness practice of 10 to 20 minutes produces measurable physiological change over eight weeks. Certain adaptogenic herbs have preliminary evidence in stress research. Ashwagandha (Withania somnifera) has shown consistent results in small trials for reducing cortisol and improving perceived stress. Rhodiola rosea has evidence for fatigue and cognitive performance under stress. Magnolia bark and L-theanine have calming effects in some studies. These are supportive tools, not treatments, and quality and dosing vary widely between products. Choose products with third-party testing certifications. Reducing caffeine, particularly afternoon and evening caffeine, helps prevent the cortisol-spiking effect of stimulants interfering with the evening wind-down. Caffeine also delays melatonin release, compounding sleep disruption.
Exercise: Getting the Balance Right
Exercise is a positive stressor that, in appropriate doses, improves HPA axis resilience. Regular moderate exercise trains the body to respond efficiently to cortisol and recover more quickly. However, high-intensity training carried out when you are already chronically stressed and sleep-deprived can worsen HPA dysregulation. Many perimenopausal women find that gentler movement, yoga, walking, swimming, and pilates, feels restorative during high-stress periods and supports recovery without adding physiological burden. This is not about avoiding intensity permanently but about calibrating your exercise load to your current recovery capacity. As sleep improves and stress reduces, gradually increasing intensity is appropriate. Listening to your body's response over days after a session, rather than just how you feel immediately after, helps you calibrate what your nervous system is ready for.
Testing for Cortisol
If cortisol dysregulation is suspected, testing can confirm whether it is present and guide intervention. Serum (blood) cortisol measured at a specific time of day gives a snapshot but misses the rhythm. A 4-point salivary cortisol test, measuring at waking, midday, late afternoon, and bedtime, maps the full daily pattern and is available through some private labs. Urinary cortisol over 24 hours is used in hospital settings primarily to rule out Cushing's syndrome (cortisol excess from a tumour), which is a different and much rarer condition. A primary care GP may be sceptical of 4-point salivary testing, as it is not standard NHS protocol, but a referral to an endocrinologist is appropriate if you suspect primary adrenal insufficiency (extreme fatigue, dizziness on standing, salt craving, weight loss, skin darkening) rather than functional dysregulation.
When to See an Endocrinologist
Most cortisol dysregulation in perimenopause responds to lifestyle intervention and does not require specialist input beyond a GP. Endocrinologist referral is warranted if blood tests suggest primary or secondary adrenal insufficiency, if morning serum cortisol is consistently very low (below 100 nmol/L), or if symptoms are severe enough to significantly impair function despite thorough lifestyle intervention. A GP who is also experienced in perimenopause medicine is often well placed to hold both conversations simultaneously: addressing HPA axis function and hormonal changes together rather than in separate silos. Keeping a detailed symptom log that captures energy levels, sleep quality, stress events, and mood across weeks and months gives any clinician the context they need to assess patterns rather than isolated data points. PeriPlan lets you log symptoms and track patterns in one place, building the record that makes those clinical conversations more productive.
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