controlled light/dark cycle light phase of controlled light/dark cycle 2014-08-26T13:10:29Z The portion of a controlled light/dark cycle in which the subject is exposed to ambient light (that is, during which the room is lit). A controlled light/dark cycle is a recurring series of conditions in which an organism experiences successive periods of exposure to controlled ambient light followed by exposure to darkness, the lack of such light, which is in turn followed by exposure to controlled ambient light and so forth. XCO:0000462 experimental_condition_ontology jsmith