A "Red Eye Flight" refers to a flight that departs late at night and arrives the next morning. These flights are popular among travelers who want to maximize their time at their destination by traveling overnight. The term "red eye" comes from the bloodshot eyes many passengers have due to lack of sleep. Typically, red eye flights are offered on routes between major cities, especially in the United States. Airlines often provide these flights to accommodate business travelers and vacationers alike. While they can save time, passengers may need to adjust their sleep schedules to cope with the overnight travel.