A monitoring device configured to be attached within a portion of an ear of a subject includes an elastomeric arm having opposite first and second end portions. A sensing element is located at the elastomeric arm second end portion and includes at least one energy emitter configured to direct energy at a target region of the ear and at least one detector configured to detect an energy response signal from the target region or a region adjacent the target region. The monitoring device is configured such that the elastomeric arm first end portion engages the ear at a first location within the ear and such that the elastomeric arm resiliently bends such that a surface of the sensing element is urged into contact with the ear at a second location within the ear.