Some individuals with body-focused repetitive behaviour disorder do these activities somewhat automatically – without thinking about it. Others are more conscious of the activity.
Individuals do not do these activities because they are obsessed with or concerned about their appearance (as occurs in body dysmorphic disorder).
However, they may feel tense or anxious just before they do them, and doing them may relieve that feeling.
Afterwards, they often feel gratified.
Individuals may also be distressed by their loss of control and repeatedly try to stop the activity or do it less often, but they cannot.
If individuals bite or pick at their nails a lot, the nails may become deformed. Grooves and ridges may develop in the nails, or blood may collect under the nail, producing a purple-black spot.