Plants are able to respond to changes in time. Among the more obvious of the clock-like responses are "sleep movements" such as the closing of flowers and changes in leaf position that many plants display at night. The movie shown here is an example of sleep movement of leaves in the common midwestern weed, velvet leaf (Abutilon theophrasti). This short movie shows leaf movements of a velvet leaf plant over a 24 hr period in continuous darkness. The plant had been grown under a 12 hr photoperiod for a few weeks before making the movie so that the plant was entrained to a 12 hr diurnal cycle. As is typical of sleep movements, the response is controlled by a circadian (biological) clock and the rhythm persists even in the absence of environmental light cues but the extent of movement decreases after a few days. This movie simply replays the first 24 hours.