Perhaps the most terrifying experience of my life came about from wanting to know what existence was like for my eldest daughter who was then aged seven. She was diagnosed as suffering from an extreme form of autism that left her almost completely in the world but not of it to the extent of being completely non-verbal - the classic changeling child of legend with a fairy-like beauty to match.

At that time she was having ever-so frequent tantrums that manifested in screaming, banging her head with her hands and against objects, arm-flapping, finger-twirling, scratching others and so on. Information on autism in New Zealand was then all but non-existent and there was absolutely no place to turn for ways to support her apart from just loving her just as she was and coping with the tantrums, meltdowns and way others judged, rebuked, shunned and ostracised her and, by extension, us.

The sense of helplessness was almost overwhelming and instead of asking the Creator, "Why?", I asked that I may experience in my own being what it was to be her and how she experienced existence that manifested in her full-body meltdowns.

My rash prayer was answered immediately. Everything that could pass through my five physical senses stampeded into me without any filter. Everything that could pass through the senses to be processed by the brain entered all at once, without distinction, without order, a complete and utter experience of chaos in sight, sound, smell, taste and touch without any filtering of intensity. It was impossible to even begin to process even the most minute fraction of what my senses were taking in to feed my brain. The sensory overload was extreme and to regain any sense of control I had to will myself to snap out of it.

Mercifully it stopped as quickly as the experience began.

Without that effort of my will I am sure that my identity would be submerged in a swirling chaos of undifferentiated sound, colour, smell, feeling and taste. I knew in the depth of my being now why my child had to withdraw into a world she could control.

I adopted all reasonable measures to limit and control the flow of sensory input to her brain. I think that I somehow decided that if her synapses could not filter neural impulses I would have to set external processes in place to apply a measure of filtering. 38 years later she is still in this world but remains not of it.

My youngest child had his 23rd birthday yesterday. He is also afflicted with neuro-atypical sensory perception but nowhere near to the degree of his older sister. In fact he is very intelligent with remarkable awareness of his neuro-atypical functioning and can communicate on a vast range of subjects that a vast number of neuro-typicals have little inkling of.

Last night we had a heart to heart conversation about what it is like to be him. When I told him about my experience many years before with his sister he said, "Yes that is it."

It is what it is.