The brain’s circadian clock is a tiny cluster of neurons behind the eyes. This cluster of cells sends out signals that control the body’s daily rhythms. New research from Harvard Medical School has started us on the path to understanding better how this process works. The possible implications of understanding how the circadian clock works are obvious. “If you could figure out the factors that promote wakefulness and sleep, that could in principle be turned into better drugs for particular sleep disorders,” said Charles Weitz, Harvard Medical School professor of neurobiology. So his research team began investigating the molecular pathway that transmits sleep and wakefulness signals. His team’s findings appeared in the Dec. 21, 2001, Science. “No one had any idea about the molecular pathway or the particular cells involved in these circadian behaviors,” said Weitz. “Now, we can mark which cells are involved and which pathway.” The seed funding for the Weitz research came from the Edward R. and Anne G. Lefler Center for the Study of Neurodegenerative Disorders within the Harvard Medical School Department of Neurobiology.