Pain sensitivity is a physiological phenomenon which allows someone to experience a sensation when something potentially harmful to the body is occurring or may occur. When a cut stings, a fire burns, and a slap tingles, sensitivity is involved. Research on pain and the mechanisms involved have shown that people have different degrees of pain sensitivity, and that a number of factors can influence the way in which someone experiences pain.
Historically, many assumptions about sensitivity to pain were rooted in ideas about relative physical or moral strength. Individuals with increased sensitivity were said to be weak, while people who were less sensitive were viewed as strong. Many cultures also believed that men were less sensitive to pain and women more so, in keeping with general social attitudes about gender identity. These beliefs held despite contradictory evidence which suggested that the situation was actually a bit more complicated.
In a 2006 study, a genetic link to pain sensitivity was discovered. Some people appear to secrete more of a chemical involved in the transmission of pain signals than others do because of a natural genetic variation. As a result, when these people are injured, they may feel more extreme pain. Other links with sensitivity to pain include neurological diseases which can heighten or decrease a person's pain threshold, and certain other medical issues as well.
Acute pain sensitivity is important. It protects the body from damage by alerting the brain to the fact that something bad is happening, allowing the brain to take rapid action. Some people have a congenital lack of sensitivity to pain, which is actually a serious problem, as they can hurt themselves quite severely without being aware of it, and internal pain signals are not transmitted either, which means that a diagnosis of a condition like appendicitis may not occur in a timely fashion.
Chronic pain is another issue. In chronic pain, people continue receiving pain signals even though the source of the pain has been removed. For example, many amputees experience lingering pain because the neurons at the amputation site get confused, and their confusion is translated into pain. In chronic pain, the constant pain is not desirable, and medications may be used to manage the experience of the pain so that the patient can enjoy more functionality. Chronic pain can be extremely debilitating for patients, and management programs can become quite complex as patients develop tolerances or bad reactions to medications used for pain management over time.