By the time she visited her doctor, Anne, a 28-year-old graduate student, had felt listless for months. Plagued by headaches, dizziness, anxiety and visual disturbances, she was struggling in her seminars and failed two exams. She also quit hobbies she enjoyed and stopped socializing. Her doctor diagnosed burnout, a depressive reaction to ongoing stress. He prescribed antidepressants and referred her to me for psychotherapy. Neither helped. A year later I suggested she go for a routine checkup to rule out any underlying physical illness. Her doctor discovered that she suffered from chronic sinusitis. After two weeks on antibiotics, Anne's infection cleared. What is more, her depression began to lift as well.