When the present or future seems overwhelming, people often look to the past nostalgically to right the ship. In other words, distress, sadness, and loss often instigate nostalgia. Johaness Hofer, a Swiss medical student, conceptualized nostalgia as a medical disease afflicting Swiss soldiers and mercenaries who had travelled from their Alpine homes to the plains of Europe to wage war. Symptoms of this disease included constant thinking about home, sadness, anxiety, irregular heartbeat, insomnia, loss of thirst, disordered eating, physical weakness, and fever. As the field of psychology grew in the early twentieth century, nostalgia was construed as an unpleasant state associated with difficulties of individuation or separation. In the late 1980s, nostalgia became a topic of empirical interest in the field of marketing. Researchers in this area discovered that throughout life people feel attached to or display preferences for the products they consumed in their late teens and early twenties.