Project Summary Sleep has been identified as a state of heightened neural plasticity, but the rules that govern reorganization during sleep remain unknown. To better identify the conditions under which synapses are pruned during sleep, we have begun to examine responses to neural injury in the fruit fly. After antennal transection, flies acutely increase their sleep for up to one day before returning back to baseline levels. Our preliminary data also show that pre-synaptic active zones are removed more rapidly than plasma membrane after antennal injury, and that sleep deprivation after injury prevents the clearance of pre-synapses from injured olfactory receptor neurons. In this project, we will examine: (1) signals that are generated after injuries to promote sleep; (2) contributions of glial cell types to sleep regulation and synapse removal after injury; and (3) molecular mechanisms that promote synapse removal during sleep. We anticipate that these experiments will provide insight into the role for sleep in response to neural trauma, and begin to investigate the consequences of disrupted sleep on recovery from axotomy.