Mood brighteners, affect tolerance, and the blues

Recently, a colleague challenged me to think seriously about a hypothetical medication--a "mood brightener...[that would] brighten the episodically 'down' moods of those who are not clinically depressed, without causing euphoria or the side effects that have accompanied the mood elevators of abuse." Fluoxetine is a significant step in that direction, he argued, and we would inevitably possess drugs that "reduce the common experiences of drudgery such as going to work on Monday mornings for those who, at present, are not seen as suffering from a mood disorder, without obvious side effects or 'impairment' in judgment." He suggested that we had best begin now to consider the implications of such medicines (R. Aranow, personal communication).