Chronic stress: what is measured, and what is sold

We have a danger-response system built for brief threats: a rapid mobilisation, then a return to balance. The contemporary problem is not the intensity of the response. It is that it never switches off.

Two systems, two speeds

Faced with a threat, two circuits activate in sequence.

The first is near-instant: the sympathetic nervous system releases adrenaline and noradrenaline. Heart rate up, pupils dilated, glucose mobilised, digestion paused. It takes a few seconds.

The second is slower: the hypothalamic-pituitary-adrenal axis, the HPA axis, ends in cortisol secretion within minutes. Cortisol mobilises energy, modulates immunity, and — this is the key point — normally exerts a negative feedback that switches off its own production.

The neurobiologist Robert Sapolsky popularised a formulation that sums up the problem: this system is very good at fleeing a predator, and very badly adapted to a workplace conflict that lasts six months. In the second case, the response does not switch off.

Why measuring your cortisol is almost pointless

Cortisol follows a marked circadian rhythm: a peak thirty to forty-five minutes after waking, a decline across the day, a minimum in the early night. A single measurement at 2pm therefore has no usable meaning. And in chronic stress the abnormality is not so much a high level as a flattened curve: a waking with no peak, an evening with no descent.

Salivary cortisol tests sold online without clinical interpretation, in a single sample, are therefore a poor investment. When a measurement is medically justified — suspected adrenal disease — it is prescribed and interpreted by a doctor, with a precise protocol.

Heart rate variability: the useful measurement at home

Your heart does not beat like a metronome. At 60 beats a minute, the interval between two beats varies constantly by a few milliseconds. That variation — heart rate variability, or HRV — reflects the balance between the sympathetic and parasympathetic systems.

As a general rule: an HRV that is relatively high for you reflects good parasympathetic tone, so a good capacity to recover; a durably lowered HRV signals an activation that is not coming back down — training load, sleep debt, alcohol, infection, psychological stress.

One trap to know: comparing your HRV with someone else’s makes no sense. Between-individual differences are considerable, linked to age, genetics and measurement position. The only valid comparison is with your own baseline.

The interventions, in order of evidence

1. Regular physical activity

This is the best documented intervention on anxiety and mild to moderate depression, with effect sizes comparable to some first-line treatments in several meta-analyses. It also improves resting HRV. Free, and by far the most effective.

2. Sleep

The relationship is two-way: stress degrades sleep, and lack of sleep increases emotional reactivity and HPA axis activation. Working on sleep is therefore an anti-stress intervention in its own right — see our piece on the three systems of sleep.

3. Slow breathing

Breathing at around six cycles a minute, with a longer exhale than inhale, amplifies respiratory sinus arrhythmia and produces a measurable acute effect on arousal. Long-term effects are more debated. But it is free, immediate, and usable in a meeting: five minutes, two to three times a day.

4. Social contact and light

Two underrated levers. Social support is a robust protective factor in cohort studies. And circadian regularity — light in the morning, darkness in the evening — stabilises the cortisol curve: see our piece on morning light.

5. Supplements, last

• L-theanine (200 mg). A reduction in situational anxiety without sedation in several trials. Emerging evidence, good tolerability, low price: the best benefit-to-risk ratio in this category.
• Omega-3 EPA/DHA. A documented effect on mild depressive mood, especially with an EPA-dominant formula. The evidence is stronger for the lipid profile than for stress itself.
• Ashwagandha. Several short trials report a fall in anxiety scores and salivary cortisol; small numbers, extracts not comparable. Emerging evidence, and real contraindications: pregnancy and breastfeeding, thyroid or autoimmune disease, liver disease.
• Magnesium. Useful where intake is insufficient, particularly for muscular tension and sleep. It is not an anxiolytic.

The line with burnout

There is a point where the vocabulary of optimisation becomes misplaced. Fatigue that no longer yields to rest, cynicism towards work that used to matter, a sense of ineffectiveness, established sleep problems, loss of interest in what used to be enjoyable: that picture is not treated with a capsule or a sensor.

In that case the levers are elsewhere: a health professional, a genuine adjustment of the load, and most often psychotherapeutic care. No product on this site replaces that — and an honest site has to write it before offering a purchase link.

The one-week protocol

1. Day 1 — Establish your baseline. Measure your HRV on waking, in the same conditions, every day. Ignore individual values for seven days.
2. Day 2 — Slow breathing. Five minutes, six cycles a minute, twice a day.
3. Day 3 — Light and schedule. Ten minutes outside on waking, fixed wake-up time.
4. Day 4 — Caffeine. Last intake eight to ten hours before bed: it raises sympathetic activation long after you stop feeling it.
5. Day 5 — Movement. Thirty minutes of moderate activity, even split up.
6. Day 6 — Alcohol. Watch the effect on the next day’s HRV. It is often the most convincing demonstration in the whole protocol.
7. Day 7 — Review. Compare the trend, not the peaks. Then, and only if one specific point resists, add one supplement for two weeks.