Not being able to sleep (this is called insomnia) can be a serious problem for people. Researchers are hoping that studying sleepy flies will teach them ways to help sleepy people.
Source: Washington University School of Medicine (2009, June 3). Insomniac Flies Resemble Sleep-deprived Humans. ScienceDaily. Retrieved June 9, 2009, from: http://www.sciencedaily.com/releases/2009/06/090602171939.htm