Do Flies and Worms Sleep? Look for an Answer Can you tell if a
fly is asleep? This is precisely the question asked seven years
ago by Dr. Joan Hendricks, who is now the Dean of the School of
Veterinary Medicine at the University of Pennsylvania. In
collaboration with Dr. Amita Sehgal and Dr. Allan Pack of the
Penn Center for Sleep and Respiratory Neurobiology (CSRN), Dr.
Hendricks wanted to determine if the fruit fly Drosophila
melanogaster, an animal used since the early 1900s for genetic
studies in biology, has a sleeplike state much as we do. But
unlike human studies, where one can measure brain electrical
activity to distinguish sleep from the waking state, one cannot
easily measure fly brain waves. Instead, Dr. Hendricks used
behavioral measures. It was already known that Drosophila are
not active all day, but rather have rest and activity patterns
that follow an approximately 24-hour, or circadian, rhythm. They
are active during the day and inactive at night, just like us.
To determine if the inactive p