The three states of the autonomic nervous system

Our nervous system is not binary; it moves between several states. In a normal situation, it oscillates between action and rest. But when faced with repeated stress, it can become dysregulated. We can then distinguish three main scenarios:

Regulating your nervous system daily

Our daily lives are saturated with invisible micro-stresses: notifications, noise, artificial light, cognitive overload. The role of modern practices is to send safety signals to the body.

Exercise and stress: ally or enemy?

Exercise is a form of stress, but a useful stress: hormesis. Properly dosed, it strengthens nervous flexibility and cortisol regulation. Improperly dosed, it maintains the state of alert.

Beneficial: zone 2 (brisk walking, gentle cycling), yoga, mobility, activities in nature that combine oxygenation and sunlight.

Dysregulating: repeated HIIT without recovery, overtraining, extreme competitions.

Deep dive: why " привыкший" stress can still overwhelm you

Animal physiology studies provide interesting insights into hormesis and its limits. In animals exposed daily to the same stress for several weeks, the sympatho-adrenal system habituates: it releases less catecholamines when faced with this familiar stress. But when faced with new and different stress, this same system reacts exaggeratedly, much more than in an animal not chronically stressed.^[6] Translated to humans, this could explain why we feel able to manage our usual stress (work, routine) while feeling completely overwhelmed by an unexpected event, even a minor one: the chronically solicited nervous system has not lost its reactivity, it has redirected it towards the unexpected.

Traditional perspectives

Ancient traditions have always placed stress management at the heart of vitality. They offer us concrete tools to understand and calm the nervous system.

Sleep and stress: a vicious circle to break

Chronic stress is one of the most powerful enemies of deep sleep. When cortisol remains elevated in the evening, it prevents melatonin secretion, making it difficult to fall asleep.

Deep dive: what research shows

The resulting sleep debt, in turn, aggravates cortisol regulation and perpetuates anxiety. It's a vicious circle that accelerates biological aging.

Individuals subjected to chronic stress have a significant reduction in deep and REM sleep phases. Poor sleep quality can increase basal cortisol levels by up to 37% the next day (Spiegel et al., Lancet, 1999).

Practical keys for Vāhana:

• Stable evening routine: turn off screens 60 minutes before bedtime, create a calming ritual (infusion, warm bath, 4-7-8 breathing).
• Circadian alignment: natural light in the morning, complete darkness at night.
• Natural supports: magnesium, L-theanine, adaptogens like ashwagandha, known to improve both stress and sleep.

Microbiota and stress: the gut-brain axis

Stress is not only experienced in the brain: it also changes the microbial ecosystem of the gut. In return, this imbalance of the microbiota amplifies anxiety, disrupts hormonal regulation, and weakens emotional resilience.

Deep dive: what research shows

Chronic stress reduces bacterial diversity and promotes the growth of pro-inflammatory strains. Certain bacteria like Lactobacillus and Bifidobacterium directly produce neurotransmitters like serotonin and GABA, essential for relaxation.

A balanced microbiota improves heart rate variability (HRV), a key marker of nervous resilience. Animal studies show that mice deprived of microbiota become hyper-reactive to stress, while probiotic recolonization normalizes their behavior.

Practical Vāhana keys:

• Consume prebiotic fibers (vegetables, legumes, roots) to nourish beneficial bacteria.
• Add fermented foods (kefir, kimchi, sauerkraut, kombucha) to strengthen microbial diversity.
• Support with calming plants (lemon balm, chamomile, tulsi) that also influence the microbiota.
• Limit refined sugar and alcohol, which feed pro-inflammatory strains.

Stress and the menstrual cycle

In women, the relationship between stress and the nervous system is complemented by a second dialogue: that with the menstrual cycle. The relationship works both ways, a classic in the scientific literature on the subject since the late 1970s.^[7]

Deep dive: what recent studies show

A 2025 study of nearly 1,800 Japanese female workers found that 54.7% of them experienced severe menstrual symptoms, and that a high workload combined with low colleague support significantly increased the risk of marked symptoms.^[8] Another study conducted during the pandemic showed that higher psychological distress was directly associated with more intense and frequent menstrual pain, even after adjusting for age and other factors.^[9]

The link also works the other way around: in women with uterine fibroids, a significantly higher perceived stress score was measured compared to women without fibroids, especially when menstrual bleeding was heavy.^[10] The cycle and the nervous system therefore influence each other, in a loop that can be self-perpetuating if nothing interrupts it.

Chronic cortisol and inflammation: two sides of the same coin

Cortisol is not the enemy. It is primarily a metabolic hormone, whose main role is to increase blood glucose; its role as a "stress signal" comes second. An acute cortisol peak, during a workout, fasting, cold exposure, or even waking up in the morning, is perfectly adaptive: it supports metabolic flexibility.

It is chronic, constantly elevated cortisol that poses a problem, and it acts on two fronts at once:

Deep dive: the self-perpetuating loop

Chronically high glucose fuels inflammation; inflammation feeds perceived stress; stress elevates cortisol; cortisol, in turn, elevates glucose. This is a self-perpetuating cycle, and it partly explains why chronic stress accelerates the body's aging: to maintain high blood glucose, cortisol eventually breaks down proteins, especially in the skin, muscles, and bones, to convert them into glucose.

To break free, you need to tackle both levers simultaneously rather than just one:

1. Glucose control: protein first, then vegetables, then carbohydrates. This is the most immediately accessible lever, detailed in the Cellular Nutrition guide.
2. Sleep: just one week of shortened sleep can measurably reduce insulin sensitivity in healthy adults, according to several controlled clinical trials^[11], and disrupt morning cortisol at the same time.
3. Breathing: ten minutes of abdominal breathing per day sends a powerful signal to the parasympathetic system, with a measurable effect on cortisol.

Relationships as a Nervous System Regulator

One safety signal that we've mentioned little so far, yet it's among the most powerful the body knows: the presence of a trusted human being. The polyvagal theory, already discussed in this guide, gives a central place to what it calls "co-regulation": one person's nervous system can literally calm another's, through tone of voice, gaze, and physical proximity.

Deep dive: a risk comparable to obesity

A meta-analysis of 90 cohort studies and over 2.2 million people independently confirms these associations.^[13] Researcher Julianne Holt-Lunstad, who led several of these foundational works, positions the risk associated with lack of social connection as comparable to, or even greater than, that of obesity as a mortality factor.

It's not just a matter of the number of contacts. The perceived quality of social support predicts health as strongly as the frequency of interactions: one trusted relationship matters more than ten superficial acquaintances.

Measuring your progress: HRV and salivary cortisol

As with the other pillars, it's possible to move beyond theory and concretely track whether your anti-stress practices are truly working, thanks to two markers measurable at home.

Heart Rate Variability (HRV)

HRV measures the interval between each heartbeat. A rigid heart beats at a constant, mechanical rhythm; a flexible heart varies slightly from one beat to the next. This variation is the parasympathetic system coming and going, telling the heart: "slow down, everything is fine." A low HRV indicates sympathetic dominance, a state of alert; a rising HRV indicates a return of the parasympathetic system, a sign that repair is resuming.

Deep dive: how to track your own HRV

This is measurable with a phone: apps like Elite HRV, Whoop, or Apple Health track this data. Measure your HRV for a week before changing anything, then again after three weeks of anti-stress practices (breathing, hot bath, meditation). If it rises, something is truly shifting.

< 20 ms

suggests chronic alert, sympathetic dominant

25-45 ms

average for those aged 60 and over

50-100 ms

average for young adults, well-established parasympathetic

HRV varies enormously depending on age, measurement device, and even time of day: therefore, compare yourself primarily to yourself over time, not to a universal standard.

Salivary Cortisol

Cortisol also follows a rhythm: in the morning, it should be high (this is what wakes you up and gets you going); in the evening, it should be low (this is what allows sleep). This is the "cortisol awakening response," followed by a natural decline throughout the day.

Deep dive: what an inverted rhythm reveals

If your cortisol is low in the morning and high in the evening, your circadian rhythm is inverted, a strong signal of chronic stress or nervous dysregulation. A simple salivary test (4 samples throughout the day) can reveal this.

Exact reference values vary greatly depending on the laboratory and the analysis method used, sometimes doubling from one source to another. What matters most, therefore, is not the absolute number, but the slope between morning and evening: a clear and steady drop throughout the day is a sign of a healthy rhythm, regardless of the exact units from the lab.

The 5 Most Important Levers

This guide has explored many avenues. Here are the 5 that offer the best balance between scientific evidence, accessibility, and real impact, chosen from everything we've covered rather than just a list of supplements.

1. Breathing

Free, available everywhere, and the best-documented in the guide. Cardiac coherence and 4-7-8 breathing balance cortisol; physiological sigh reduces amygdala activation; humming (Bhramari breathing) directly stimulates the vagus nerve through vocal cord vibration, with a measured stress index lower than during sleep.

2. Yoga

The most well-supported practice among all mind-body movements: it stimulates vagal afferents, improves baroreflex sensitivity, and regulates the hypothalamic-pituitary-adrenal axis, with a measurable decrease in cortisol in the most robust meta-analyses on exercise and stress.^[12]

3. Protecting your sleep

The foundational lever that influences all others: just one week of shortened sleep is enough to measurably reduce insulin sensitivity and disrupt morning cortisol.^[11] Practical details in the Recovery & Biorhythms guide.

4. Magnesium

The best evidence-to-cost ratio among supplements. Glycinate in the evening to relieve tension and prepare for sleep; threonate earlier in the day for anxiety and mental clarity. A systematic review confirms consistent improvement in self-reported anxiety across 15 clinical trials.^[4]

5. Tapping (EFT)

A unique mechanism in this top 5: gentle stimulation of acupressure points combined with cognitive restructuring. Several independent meta-analyses show a significant reduction in anxiety and psychological distress, with substantial effect sizes.^[5] Tap with your fingertips on about ten points (scalp, eyebrow, temple, under the eye, chin, collarbone) while verbally acknowledging what is weighing on you.

This is not an exhaustive list of what could have been explored further elsewhere: ashwagandha and rhodiola (classic adaptogens), saffron and omega-3 (mood), vitamin D (in case of deficiency), creatine (cognitive resilience under stress), cocoa, essential oils, valerian (with caution on CBD depending on your jurisdiction), 5-HTP (never with an antidepressant), dancing and singing, somatic approaches like TRE. Each has its place and its own evidence, but the 5 levers above remain the strongest starting point to begin with.

Vāhana Anti-Stress Routine

Recommended Readings and Resources

Scientific References

Got a question? We have answers

How do I know if I'm in survival mode?

Constant tension, light sleep, disturbed digestion, excessive vigilance.

And in shutdown mode?

Extreme fatigue, emotional disconnection, loss of motivation.

What's the first step to getting out?

An immediate safety signal: 4-7-8 breathing, hot bath, natural light, mindful walking.

Is stress always negative?

No. Acute stress can stimulate adaptation, performance, and even immunity. It is chronic, constant, unresolved stress that damages tissues, deregulates hormones, and accelerates aging.

Do breathing techniques have a real scientific effect?

Yes. Several studies show that practices like cardiac coherence or 4-7-8 breathing reduce cortisol, activate the vagus nerve, and promote nervous system balance.

Go further

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