A monitoring device includes a band capable of encircling a portion of the body of a subject, and an optical emitter and detector attached to the band. The band includes comprises light transmissive material in optical communication with the optical emitter and optical detector and is configured to deliver light from the optical emitter to one or more locations of the body of the subject and to collect light from one or more locations of the body of the subject and deliver the collected light to the optical detector. The monitoring device may include a signal processor configured to receive and process signals produced by the optical detector, a transmitter configured to transmit signals processed by the signal processor to a remote device, and/or an optical filter.