A method for monitoring a biological parameter out of either the heartbeat and/or respiratory signal of an occupant on a member of a seat or bed, wherein a signal or signals received from one or a plurality of sensors connected to the member and capable of detecting the variation of pressure due to contact are processed by non-linear filtering. For example, the method is mounted on a vehicle and used. Also provided is a computer program including code instructions capable of controlling execution of the method of the invention when the method is executed by a computer. Further provided is a monitoring device for monitoring a biological parameter out of either the heartbeat and/or respiratory signal of an occupant on a member of a seat or bed.