The Sniff Test for Mental Illness

Imagine a patient goes to see his general practitioner, complaining of exhaustion. He can't sleep, and he'd like a referral to a sleep clinic so he can get some answers. First, his doctor wants to administer a quick test. She holds a device like a felt-tipped pen just under her patient's nose and has him sniff. "Sure, I can smell that," he says. She gives him three pens and asks which one smells different from the other two. "They all smell like peppermint to me," the patient says. "Okay," the doctor says, "I'm referring you to a psychiatrist."