It's a metaphor. If LIFE is a JOURNEY, falling is an interruption, possibly a fatal one, depending on how far one falls. In any event, falling is an event where people lose control, and that's the critical component for falling asleep, in love, for somebody, away from something, etc. In each of these cases, one is not an actor but a patient. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.