Scores of historical and philosophical studies have been devoted to dreams. However, the notion of deep sleep (as opposed to dreams) seems to have been thoroughly neglected. The present study attempts to fill this gap by analyzing representations of sleepers and theories of sleep in the Renaissance. My working hypothesis is that even though deep sleep appears to be located outside of the realm of consciousness, it amounts nonetheless to a heavily determined notion, both semantically and axiologically. Sleep seems to offer a form of imaginative diversion, as the absence of knowledge gives free rein to fanciful metaphors. At the crossroads of Christian and pagan traditions, Renaissance art offers a cornucopia of representations of sleep. They constitute visual metaphors, deeply influenced by the literature and theoretical writings of the period, on which they had in turn a tremendous impact. Thus, sleep is often equated with sin, as « idle hands are the devil's workshop », but its meaning also depends on the sleeper's attitude, location and context. For instance, sleep can be depicted as an emblem of early childhood or old age (first or last sleep), a metaphor for oblivion (Lethean sleep), a figure of ecstasy and faith (contemplative rest), an image of melancholy (sleep of sadness), of spiritual rapture (vacation of the soul) or sensual ravishment (lethargic eroticism). Whichever the case, sleep always remains an enigma, a Protean concept assuming the shape of virtually unanswerable questions : lethargic images of happiness, love and death that are still haunting the contemporary imagination, « absolute metaphors » constantly reinventing themselves and their history.