Embodiments of the present invention provide a ring for sensing one or more physiological and/or behavioural parameters of a user. The ring comprises an aperture for receiving a finger of the use. The aperture comprises a sensing portion, one or more sensing means disposed in the sensing portion and a resiliently deformable pad opposing the sensing portion. The resiliently deformable pad is arranged to contact a finger to pressure the finger against the one or more sensing means when the finger is received in the aperture. Aspects of the invention relate to a trigger device, to an apparatus for inducing sleep and to a kit.
