A detection device, for placement under or on a mattress, configured for the movements of a person lying on the mattress, includes a sensing portion having an inflatable chamber intended to be positioned under the individual, an electronic unit arranged at a distance from the sensing portion and having a pressure sensor, intended to be positioned outside of the bedding, a transmitting portion interposed between the sensing portion and the electronic unit, including a channel establishing a fluid connection between the inflatable chamber and the sensor, the channel having a transverse dimension (T) that is much smaller than the width (L1) of the chamber.
