Sensory Behaviour and the Nervous System

How can we assist sensory defensive children to settle and to cope in a more typical fashion? In this article, we take a look at some of the underlying physiology and autonomic nervous system activity which is thought to be involved in sensory avoidant behaviours, as well as some of the neurotransmitters and hormones that seem to play a role when children display defensive reactions and inappropriate behaviour in response to uncomfortable sensory input. We also look at some different ways of helping children to make positive shifts by impacting on these systems.

Children who present with sensory avoidance often avoid giving and receiving hugs. They may also be defensive to touch and may be fussy about textures of clothing, be fussy about labels, and could really dislike getting dirty. They may also be easily upset by loud sounds and crowd situations. These typical features of sensory defensiveness are part of a much longer list of typical features described by parents and teachers of children who experience sensory processing difficulties. Exposure to such sensory input often results in explosive emotional outbursts, tantrums and meltdowns, which may also include aggressive behaviour and other inappropriate social behaviour.

If we were to explore their physiology in a little more detail, we would likely find that these children also show far more signs of sympathetic nervous system activity, than would be the case for most typical children. The sympathetic nervous system prepares us for flight and fright reactions, and helps us to keep ourselves safe in the midst of dangerous or life-threatening situations. In a split-second, our bodies can be ready to run away extremely quickly, or to push, shove, and thrust away any offending person or threat, and to fight our way to safety. When our sympathetic nervous system predominates, we shift into surveillance mode, and our bodies become super-alert to sensory cues which give us more information about possible danger around us. We notice sounds, smells and light touch sensations far more acutely than usual. Loud sounds frighten us more than usual. High and low pitched sounds become scary and disorganise us. This is because our nervous system recognises these signals, such as a high pitched scream, as signs of possible danger. Our bodies respond with a flood of stress biochemistry that keeps us ready to fight, flee, or to defend ourselves. For some children, the high pitched sounds of other children shrieking or crying can trigger the fright or flight nervous system. When children remain in this stressed state of sympathetic nervous system activity coupled with sensory hypervigilance and hyper-reactivity, they can find it very difficult to relax and to settle. Their behaviour is often disorganised and they are easily disrupted. These children are also more likely to lash out and to fight as they strive to protect themselves in this apparent “survival” situation.

So how can we bring about order and calm for the Sensory Defensive Child?

If we could counter the effect of an over-reactive sympathetic nervous system, we could help to reduce sensory avoidance and associated inappropriate behaviours. Let’s take a look at the effects of the parasympathetic nervous system as well as looking at the effects of some important hormones and neurotransmitters that can also have an organising effect for the overly-sensitive child.

When the parasympathetic nervous system or calm, peacekeeping nervous system predominates, we can drift to sleep easily, and we enjoy long restful undisrupted sleep. Our digestive system depends on the effects of the parasympathetic nervous system for the secretion of digestive juices and for the digestive movements of smooth muscle in the gut. Our heartbeat and blood pressure is also kept in check through the effects of the parasympathetic nervous system. We can engage this “rest, digest, and repair” system through providing a calm relaxed environment, through gentle rocking, soft pleasant music with a beat of around 70bpm, and through deep touch pressure and non-stressful heavy muscle work.

The calm and organising parasympathetic nervous system can be facilitated by stimulating the vagus nerve. This nerve, which contributes to providing parasympathetic nervous system input to the body, originates in the brainstem and weaves its way down through the neck, chest area and abdomen, supplying organising input to just about all the organs in the body.

We can nudge the vagus nerve into action through deep diaphragmatic breathing. So getting the child to take big slow breaths that expand right down into his belly can switch on the effects of the vagus nerve. Singing and humming also facilitate the effects of the vagus nerve. So does gargling! Moving and wetting the tongue also gets the vagus nerve active. For most people, thinking about sucking on a lemon is enough to get the saliva glands and tongue going, and this simple thought can switch on the organising effects of the vagus nerve!

Face-to-face happy social interaction is important in facilitating vagal tone. When we display a caring attitude towards each other, we stimulate a positive vagal tone effect in our bodies. When we feel emotionally connected to others, our vagal tone rises. Experiencing positive emotions also raises our vagal tone.  Similarly, experiencing gratitude and a sense of well-being, stimulates the vagal nerve “feel good” response. Meditation and positive mindfulness can also promote a positive sense of wellbeing and also facilitate a vagal nerve response.  So, being mindful in these ways, and avoiding focussing on negative stuff, can really be good for us!

Maintaining an active routine of daily physical activity such as going for a brisk walk, or taking part in 30 minutes of gently raised cardio activity can also be most helpful in reducing the harmful effects of on-going and unabated sympathetic nervous system activity.  A “diet” of organising sensory activities throughout the day can also contribute immensely to keeping a child more organised.

Switching on Happy Biochemistry and Neurochemistry

Serotonin is a neurotransmitter, which, when released in just the right proportions and in the right manner, can assist in keeping us in a happy disposition.  Deep pressure massage and deep pressure brushing are known to result in the release of Serotonin.

Oxytocin is both a hormone and a neurotransmitter which is involved in birth, breastfeeding, is essential in the vital process of infant attachment and bonding, as well as in promoting  promoting “rest and digest” and a sense of trust and emotional wellbeing. It is also involved in reducing anxiety and the presence of oxytocin promotes wound healing. . Oxytocin is released in situations in which we show compassion, care for each other and in which we support each other emotionally. It promotes social trust. Being touched, stroked and hugged by loved ones, promotes the release of oxytocin.

Dopamine is the feel-good “reward” neurotransmitter in the brain which is released in response to our feeling a sense of achievement or success. It is released in response to feeling satisfied for a job well done, and is responsible for the warm glow which we feel when we are praised or acknowledged. By carefully acknowledging a child’s effort and small successes along the way, we can harness the positive reward effect of dopamine, and help to keep the child focussed and attentive.

So, with all the above in mind, we can make a difference to sensory defensive children by reassuring them and offering them a safe and secure space where things are predictable.  We can provide a space where the sensory input is more organised and less alerting.  Turn down the noise level. Reduce unnecessary light touch input, and avoid all tickling.   Play gentle music at a low volume and encourage singing. Gently rock, or gently bounce the child to provide some organising movement input. Offer deep pressure massage when the child is ready to accept this.  Try some of the easy suggestions to increase vagal tone.

Many of the solutions are in fact quite simple, and could also go a long way to building well-integrated emotionally resilient children.  The positive effects of therapy can be greatly enhanced by implementing some or all of the above suggestions.