Interesting theology of sleep (as a typology of death) – A Treatise on the Soul, chap. 43:
If you receive your instruction from God, (you will find) that the fountain of the human race, Adam, had a taste of drowsiness before having a draught of repose; slept before he laboured, or even before he ate, nay, even before he spoke; in order that men may see that sleep is a natural feature and function, and one which has actually precedence over all the natural faculties. From this primary instance also we are led to trace even then the image of death in sleep. For as Adam was a figure of Christ, Adam’s sleep shadowed out the death of Christ, who was to sleep a mortal slumber, that from the wound inflicted on His side might, in like manner (as Eve was formed), be typified the church, the true mother of the living. This is why sleep is so salutary, so rational, and is actually formed into the model of that death which is general and common to the race of man. God, indeed, has willed (and it may be said in passing that He has, generally, in His dispensations brought nothing to pass without such types and shadows) to set before us, in a manner more fully and completely than Plato’s example, by daily recurrence the outlines of man’s state, especially concerning the beginning and the termination thereof; thus stretching out the hand to help our faith more readily by types and parables, not in words only, but also in things. He accordingly sets before your view the human body stricken by the friendly power of slumber, prostrated by the kindly necessity of repose immoveable in position, just as it lay previous to life, and just as it will lie after life is past: there it lies as an attestation of its form when first moulded, and of its condition when at last buried-awaiting the soul in both stages, in the former previous to its bestowal, in the latter after its recent withdrawal. Meanwhile the soul is circumstanced in such a manner as to seem to be elsewhere active, learning to bear future absence by a dissembling of its presence for the moment. We shall soon know the case of Hermotimus. But yet it dreams in the interval. Whence then its dreams? The fact is, it cannot rest or be idle altogether, nor does it confine to the still hours of sleep the nature of its immortality. It proves itself to possess a constant motion; it travels over land and sea, it trades, it is excited, it labours, it plays, it grieves, it rejoices, it follows pursuits lawful and unlawful; it shows what very great power it has even without the body, how well equipped it is with members of its own, although betraying at the same time the need it has of impressing on some body its activity again. Accordingly, when the body shakes off its slumber, it asserts before your eye the resurrection of the dead by its own resumption of its natural functions. Such, therefore, must be both the natural reason and the reasonable nature of sleep. If you only regard it as the image of death, you initiate faith, you nourish hope, you learn both how to die and how to live, you learn watchfulness, even while you sleep (emphasis added).