Nell (not her real name) was shivering, but she did not realize she was cold. Only when a colleague pointed out her goose bumps and blue lips did she think to put on a sweater. Nor does she register feelings such as exhaustion. “Sometimes I don’t realize I’m tired until three in the morning,” she says. “I just don’t get those clues correctly.”
These traits seemed like little more than quirks until September 2010, when the 36-year-old woman took a full battery of psychological tests as she reentered treatment for a relapse of anorexia nervosa, a disorder she had struggled with on and off for more than 20 years. One of the tests included a section measuring a little-known sense called interoception, awareness of the internal state of one’s body. Interoception informs us of emotions, pain, thirst, hunger and body temperature. People vary on how well they receive such cues. As with other individuals who have eating disorders and body image issues, Nell showed profound difficulties with interoception.