Stress in Autism: From Fight or Flight to Rest, Digest and Reconnect.

The autonomic nervous system runs quietly in the background, controlling things like

heart rate, breathing, digestion, and blood flow. It has two main branches that work like a

see-saw to keep the body in balance. The sympathetic nervous system is our body’s

“fight or flight” system—designed to keep us safe in times of stress or danger. It speeds

things up, sending energy to the muscles, heart, and brain so we can act quickly. The

parasympathetic nervous system, on the other hand, is our “rest, digest, and

connect” mode. It slows things down, allowing the body to repair, digest, sleep, and

grow. Ideally, these systems move in and out of balance throughout the day. But when the sympathetic nervous system stays switched on too long, the body’s physiology changes in ways that affect nearly every organ system. This is known as a chronic stress response and is very common in people with autism.

Physiological Effects of Sympathetic Dominance

1. Brain and Nervous System

• Increased cortisol and adrenaline heighten alertness, anxiety, and vigilance, but

reduce the brain’s ability to learn, socialise, and regulate emotions.

• Blood flow shifts away from the prefrontal cortex (responsible for reasoning,

empathy, and self-control) toward the limbic system (fear and survival centres).

• Reduced neuroplasticity – chronic stress hormones inhibit growth of new neural

connections and myelination, limiting brain development in children.

• Altered vagal tone – low vagal activity means less parasympathetic “braking,”

contributing to poor emotional regulation and digestive motility.

• Retained primitive reflexes may persist or reappear due to chronic motor system

hypervigilance.

2. Cardiovascular System

• Increased heart rate (tachycardia) and blood pressure to enhance blood flow to

muscles.

• Vasoconstriction in skin and digestive organs; vasodilation in skeletal muscles

and heart.

• Increased cardiac workload over time can contribute to arrhythmias, endothelial

dysfunction, and hypertension in adults.

3. Respiratory System

• Rapid, shallow breathing replaces diaphragmatic breathing.

• Leads to reduced oxygen exchange and respiratory alkalosis, which can cause

dizziness, tingling, or anxiety sensations.

• Chest breathing activates neck and shoulder tension; reduced vagal input to the

diaphragm further weakens parasympathetic tone.

4. Digestive System

• Reduced gastric acid and enzyme secretion, slowing digestion and nutrient

absorption.

• Decreased peristalsis (gut movement) – constipation or alternating constipation

and diarrhoea.

• Tightened sphincters (especially the lower oesophageal sphincter), increasing

reflux risk.

• Reduced bile flow – poor fat digestion, gallbladder stasis, and increased microbial

imbalance.

• Leaky gut – stress hormones disrupt tight junctions (via zonulin and mast cell

activation), increasing gut permeability and inflammation.

• Dysbiosis – beneficial gut bacteria decline, while opportunistic species (e.g.

Clostridia, Bacteroides) flourish.

5. Endocrine System

• Elevated cortisol and adrenaline suppress reproductive and thyroid hormones.

• Reduced insulin sensitivity and increased blood glucose to fuel the “emergency.”

• Chronic cortisol dysregulates circadian rhythm, sleep, and appetite hormones

(leptin, ghrelin).

• DHEA and melatonin production often drop, affecting mood, immunity, and sleep.

6. Immune System

• Initially stimulated, then suppressed with chronic activation.

• Increased inflammatory cytokines (IL-6, TNF-α) and oxidative stress damage

tissues and the blood–brain barrier.

Amanda Downsborough, MScwww.brainkids.com.au

• Reduced mucosal immunity (IgA) weakens gut and respiratory defences.

• Microglial activation in the brain perpetuates neuroinflammation — a key issue in

autism and chronic illness.

• Allergic or autoimmune flares may worsen due to immune dysregulation and gut

permeability.

7. Musculoskeletal System

• Chronic muscle tension in the neck, shoulders, and jaw.

• Increased tone in flexor muscles (protective posture).

• Reduced fine motor control and coordination as gross motor “escape” patterns

dominate.

• Fatigue and soreness from lactic acid buildup and poor recovery.

8. Reproductive System

• Suppressed reproductive hormones (FSH, LH, oestrogen, testosterone) as the

body prioritises survival.

• In females: irregular or painful cycles, delayed puberty, or reduced fertility.

• In males: lowered testosterone and sperm quality.

9. Skin and Peripheral Circulation

• Pale, cool skin due to vasoconstriction.

• Sweating increases, especially palms and soles.

• Slower wound healing due to reduced perfusion and immune function.

10. Detoxification and Cellular Function

• Reduced liver blood flow and bile output impair detoxification pathways.

• Mitochondrial function declines, reducing ATP production, brain connection

growth, and ability to remove heavy metals.

• Oxidative stress increases, contributing to fatigue, “brain fog,” and inflammatory

cascades.

11. Sleep and Circadian Rhythm

• Difficulty falling or staying asleep (high evening cortisol, low melatonin).

• Fragmented REM sleep reduces memory consolidation and emotional

processing.

• Children may appear “wired but tired.”

12. Behavioural and Emotional Patterns

• Hyperarousal, impulsivity, meltdowns, or shutdowns as the body oscillates

between sympathetic and dorsal vagal responses.

• Reduced eye contact, play, and social engagement due to poor

parasympathetic activation.

• Difficulty transitioning between activities or environments.

Sympathetic dominance keeps the body in “survival” mode. Over time, this state alters how the brain wires, the gut digests, the immune system reacts, and the child connects. Restoring parasympathetic balance isn’t just about calm — it’s about healing and growth at every level.

Ways to Restore Parasympathetic Balance

(for both children and parents)

1. Rhythmic, Deep Breathing

• Teach 4–7–8 breathing. Breathe in through the nose for 4 seconds, hold for 7, and

slowly exhale through the mouth for 8 seconds. Repeat 3 times.

• Slow exhalations (longer than inhalations) directly activate the vagus nerve.

• Parents can co-breathe with children — your calm rhythm becomes theirs.

2. Movement that Feels Safe

• Rocking, swinging, crawling, balancing, gentle yoga, or animal walks.

• Encourage bilateral movements (crossing midline) to engage both brain

hemispheres.

• Walking outdoors — especially barefoot on grass or sand — resets the stress

response.

3. Touch and Connection

• Hugs, massage, brushing, or weighted blankets (if tolerated).

• Gentle physical contact activates oxytocin and vagal pathways.

• For parents: take slow hugs with deep breaths — it rebalances you both.

4. Nature and Sensory Grounding

• Sunlight, fresh air, and natural sounds (waves, wind, birdsong).

• Gardening, barefoot time, or lying on the ground helps discharge stored tension.

• Encourage slow observation — looking at clouds, feeling textures, noticing smells.

5. Laughter and Play

• Laughter resets the vagus nerve and raises endorphins.

• Shared humour and silly play create emotional safety and joy — essential for

learning and bonding.

6. Predictability and Rhythm

• Regular meal, sleep, and activity times support circadian and vagal rhythm.

• Visual routines and gentle transitions help children feel safe and settled.

7. Nutrition and Gut Support

• Whole, unprocessed foods; regular meals to stabilise blood sugar.

• Include omega-3 fats, magnesium, and B vitamins for nervous system support.

• Warm, slow meals (not rushed) encourage digestive activation.

8. Co-Regulation

• A calm parent nervous system teaches a child’s system how to return to calm.

• Model deep breathing, soft tone, and relaxed posture.

• Remember: you are your child’s emotional anchor.

9. Creative and Emotional Expression

• Drawing, music, singing, dancing, journalling.

• Expressing emotion releases tension from the nervous system and supports right-

hemisphere integration.

10. Rest and Sleep Hygiene

• Create a calm evening routine — dim lights, no screens, gentle stories or music.

• For parents, prioritise wind-down rituals (stretching, herbal tea, gratitude

journaling).

11. Cold and Warm Therapy

• Gentle contrast therapy (e.g., splash of cool water on the face or neck, warm

baths) can stimulate vagal tone.

• Never extreme — just mild sensations to nudge the body toward balance.

12. Mindfulness and Presence

• Guided meditations, mindfulness colouring, or simple awareness of breath.

• Even two mindful minutes several times a day strengthen parasympathetic tone.

• Children benefit from short, playful mindfulness (e.g., “feel your toes breathe!”).

Activating the parasympathetic nervous system is about safety, connection, and recovery. It’s not just rest — it’s the state where healing, learning, and love happen.

For children with autism or anxiety, spending more time in this state allows the brain to

rewire, the gut to heal, and the heart to open.

For parents, restoring your own calm is the greatest therapy you can offer your child — your nervous system is the model they learn from every day.

For parents ready to take this understanding even further, these next tools can be life-changing. The vestibular system and the vagus nerve form the body’s natural calming network — learning how to work with them gives you a direct way to

help your child’s body find balance again.

The vestibular system and the vagus nerve are the body’s hidden allies — one helps your child feel where they are in space, the other tells the brain it’s safe to relax.

Body Awareness, Vestibular System, and the Vagus Nerve

• The vestibular system (inner ear balance organs) connects directly with brainstem

nuclei that also regulate autonomic function — including the vagus.

• When the vestibular system is gently activated (e.g., rocking, spinning, swinging), it

can either stimulate or settle arousal, depending on the direction, speed, and the child’s sensory profile.

• For many autistic children, spinning in one direction only, or rocking rhythmically, can actually reduce fight-or-flight activation by improving cerebellar

and brainstem integration.

• Movement also improves proprioceptive feedback — helping them feel where their body is, which naturally enhances safety and vagal tone.

The Diaphragm and Vagus Nerve Connection

The diaphragm is one of the most powerful access points to the parasympathetic system because the vagus nerve passes directly through it.

• When the diaphragm is tight or underused (due to shallow breathing, stress, or

posture), vagal signalling weakens.

• Diaphragm release or massage can restore movement, improve oxygenation,

and reawaken parasympathetic pathways.

Gentle Diaphragm Massage

(Always do this as gentle body awareness — not a “deep tissue” approach.)

1. Have the child or parent lie comfortably on their back.

2. Place fingertips just under the ribcage in the soft area of the upper abdomen.

3. Encourage slow breathing — in through the nose, out through the mouth.

4. On each exhale, gently sink the fingertips upward and inward beneath the ribs

(toward the diaphragm).

5. Hold for a few seconds, then release and repeat several times.

6. You may feel the diaphragm move or “let go” slightly over several breaths.

This gentle release can:

• Stimulate the vagus nerve via mechanoreceptors.

• Improve gut motility and reduce bloating.

• Enhance awareness of breathing and internal sensations (interoception).

⚠ Avoid direct pressure if there’s reflux, hernia, abdominal pain, or recent surgery.

Auricular (Ear) Vagus Nerve Stimulation Points

The auricular branch of the vagus nerve (ABVN) innervates specific areas of the outer

ear. Stimulation here — even manually or with gentle vibration — can increase vagal activity and calm the nervous system.

Key Areas:

• Behind the ear (mastoid area) – where the vagus nerve branches near the

auricular cartilage and mastoid bone.

• Inner tragus and cymba conchae (the small hollow just inside the ear) – most

directly innervated by the ABVN.

Simple Parent-Friendly Approaches:

Gentle massage behind the ears:

◦ Using the thumb and forefinger, apply slow circular motions just behind and

slightly below the ear lobe.

◦ Combine with slow breathing — this enhances the vagal effect.

Warm compress behind the ears:

◦ Applying gentle warmth (not heat) encourages blood flow and relaxation.

Gentle tapping or brushing:

◦ Use a soft brush or fingertip tapping rhythmically behind and around the

ears.

◦ Many children find this soothing before sleep.

Ear–jaw release:

◦ Gentle jaw opening and closing, or humming, also vibrates the same nerve

pathways.

Pairing Vestibular and Vagal Techniques

When combined, these approaches can be transformative:

• Spinning or rocking + slow breathing = vestibular + vagal co-regulation.

• Humming or singing while spinning slowly = vibrational + diaphragmatic

stimulation.

• Parent–child rhythmic rocking = co-regulation through vestibular, tactile, and

emotional safety cues.

These activities build body awareness, calm, and connection — the true triad of healing

in autism and nervous system regulation.

Amanda Downsborough, BSc, PGDip, GCert, MSc, ACAAM,

Functional & Nutrigenomic Medicine Practitioner

Brain Kids – www.brainkids.com.au

About the Author

Amanda Downsborough, BSc, PGDip, GCert, MSc, ACAAM, is a Functional and Nutrigenomic Medicine Practitioner specialising in autism and child neurodevelopment. Through her practice, Brain Kids, Amanda combines functional medicine and neuroscience to uncover the biochemical and environmental factors affecting children’s health. Her work empowers families with science-based strategies to support brain balance, behaviour, and lifelong wellbeing.

Disclaimer

This information is provided for educational purposes only and is not intended as a

substitute for medical advice, diagnosis, or treatment. Always seek the advice of a

qualified healthcare provider with any questions regarding a medical condition or before

making changes to your or your child’s care plan.