Systems, methods and media for detecting a seizure use one or more 3D cameras to monitor an individual. The 3D cameras may movements associated with the tonic or clonic phases of a seizure. A detection zone is used to monitor the individual via the one or more 3D cameras. As the individual moves, the detection zone is automatically adjusted such that zone remains around the person. Detected body position and/or movements, including rate of movement and duration of movement, consistent with a seizure may cause the system or media to alert the individual, a central monitoring system, caregivers, and/or others.