"To think in this manner is to augment our existence, as instead of reckoning a third of our life mere waste, we habituate ourselves to attend to the result of our hours past in Sleep, and to recover out of the mass of thought produced during that period, very often amusement, and sometimes useful instruction, nor are we to be without expectation that at some extraordinary times we may have impressions made upon our minds in Sleep so strong as may persuade us to act in consequence of them, and thereby to attain good or avoid evil."
— Boswell, James (1740-1795)
(II, p. 117 in SUP edition)
See also James Boswell, The Hypochondriack, ed. Margery Bailey, 2 vols. (Stanford UP, 1928)