Apparatus for providing transcutaneous electrical nerve stimulation (TENS) therapy to a user, said apparatus comprising: a housing; an application unit for providing mechanical coupling between the housing and the user's body; a stimulation unit for electrically stimulating at least one nerve of the user; a sensing unit for (i) sensing the user's body movement and body orientation to determine whether the user is in an “out-of-bed” state or a “rest-in-bed” state, and (ii) analyzing the sleep characteristics of the user during the “rest-in-bed” state; and a feedback unit for at least one of (i) providing the user with feedback in response to the analysis of the sleep characteristics of the user, and (ii) modifying the electrical stimulation provided to the user by the stimulation unit in response to the analysis of the sleep characteristics of the user; wherein the sleep characteristics comprise a likelihood measure of the user's sleep quality.