In this paper, we describe a monitoring system for bedridden persons that utilize a proximity range sensor with an infrared projector and is capable of detecting persons awakening and/or falling out of bed. The system, which utilizes an optimal linear discriminant function, has demonstrated a detection rate of 98% for the targeted behaviors. It is believed that this system will be useful for monitoring seriously ill and/or elderly persons in hospitals and private homes that must occasionally be left unsupervised by healthcare professionals or family members. The wandering of elderly persons suffering from dementia can also be detected and averted.