Highly sensitive people or HSPs are thought to experience emotions more deeply, and feel more intensely stimuli such as odors, sound, and light. Some researchers believe that there is a spectrum of sensitivity, and those who are highly sensitive simply lie at the far end of the sensitivity spectrum. Overall, 20 % of people are thought to be highly sensitive, and there are equal numbers of men and women sharing this trait.
It is thought that the neurotransmitter serotonin may play a role in the development of high sensitivity. This neurotransmitter contributes to regulation of mood and sleep. Additional factors such as temperament and personality may be important for HSP as well.
Is there a benefit to being overly sensitive? HSPs may notice and enjoy subtleties more, and are sometimes more gifted in the arts and interpersonal communication as a result. However, according to this research, HSPs may also become easily overwhelmed by sensory input. More research is needed regarding potential relationships between this trait and disorders such as fibromyalgia and chronic fatigue.