What causes hair-grooming syncope?
Hair-grooming syncope is believed to be a type of reflex syncope. In this type of syncope, fainting happens due to a specific trigger. Some examples of potential triggers include:
Hair grooming is a less common syncope trigger. For example, a 2019 study found that only 2.26 percent of the 354 people in the study had experienced hair-grooming syncope. In this study, actions like urinating and having a bowel movement more commonly led to fainting.
The exact mechanism that causes hair-grooming syncope is unclear. Perhaps in some people, activation of multiple nerves in the scalp and face during grooming causes a reaction in the body similar to that of other syncope triggers.
This reaction can cause a drop in heart rate and widening of blood vessels, leading to a decrease in blood pressure. Blood flow to the brain can then drop, particularly if you’re standing up, and you can briefly lose consciousness.