High sensitivity is a minority temperament trait, present from birth and found in 15-20% of the population. Experienced by too many of us to be considered a “disorder”, but not enough of us to be well understood by the majority. It’s divided equally between males and females and biologists have discovered its existence in over 100 animal species. The trait reflects a certain type of survival strategy: being observant before reacting. The scientific term is Sensory Processing Sensitivity (as distinct from Sensory Processing Disorder).
A highly sensitive nervous system is wired to detect absolutely everything in the environment and react accordingly. These children notice MORE through all senses, including the emotional cues of others, process the information more thoroughly and deeply in the brain and more quickly in the spinal cord and therefore have stronger emotional reactions to these stimuli. The key word is MORE.