Homesickness is the distress caused by being away from home. Its cognitive hallmark is preoccupying thoughts of home and attachment objects. Sufferers typically report a combination of depressive and anxious symptoms, withdrawn behavior and difficulty focusing on topics unrelated to home. Experienced by children and adults, the affected person may be taking a short trip to a nearby place, such as summer camp, or they may be taking a long trip or have moved to a different country. In its mild form, homesickness prompts the development of coping skills and motivates healthy attachment behaviors, such as renewing contact with loved ones. Nearly all people miss something about home when they are away, making homesickness a nearly universal experience. However, intense homesickness can be painful and debilitating. Historical references Homesickness is an ancient phenomenon, mentioned in both the Old Testament books of Exodus and Psalm 137:1 ("By the rivers of Babylon, there we sat down, yea, we wept, when we remembered Zion") as well as Homer's Odyssey, whose opening scene features Athena arguing with Zeus to bring Odysseus home because he is homesick ("...longing for his wife and his homecoming..."). The Greek physician Hippocrates (ca. 460–377 BC) believed that homesickness—also called "heimveh" (from German "Heimweh") or a "nostalgic reaction"—was caused by a surfeit of black bile in the blood. In recent history, homesickness is first mentioned specifically with Swiss people being abroad in Europe ("Heimweh") for a longer period of time in a document dating back to 1651. This was a normal phenomenon among the many common Swiss mercenaries serving in different countries and many rulers across Europe at that time. It was not uncommon for them staying many years away from home and, if lucky enough, return home if still alive. This phenomenon at that time was first only thought to affect Swiss people until this was revised, probably caused by big migration streams across Europe suggesting the same symptoms and thus homesickness found its way into general German medical literature in the 19th century. American contemporary histories, such as Susan J. Matt's Homesickness: An American History, describe experiences of homesickness in colonists, immigrants, gold miners, soldiers, explorers and others spending time away from home. First understood as a brain lesion, homesickness is now known to be a form of normative psychopathology that reflects the strength of a person's attachment to home, native culture and loved ones, as well as