A bed or chair exit sensing device to be placed in, on or in relation to a bed or chair, and adapted to detect a person leaving the bed or chair, comprising a piezoelectric sensor and a data processing device adapted to determine, by processing the signals from the piezoelectric sensor, when the person is leaving the bed, characterized in that the bed or chair exit sensing device comprises an accelerometer sensor, and said data processing device is adapted to determine bed or chair exit of a person on the basis of combined processing of the signal from said piezoelectric sensor and the signal from said accelerometer sensor.