"Caffeine and the Coming of the Enlightenment" by Roger Schmidt, in Raritan (Summer 2003), Rutgers University, 31 Mine St., New Brunswick, N.J. 08903.
"Short, O short then be thy reign/And give us to the world again!" That's the great Samuel Johnson, flinging his defiance at sleep during one of his famous nocturnal excursions, in 1753. The storied man of letters is nearly as famous for his vast capacity for late-night reading and carousing as for his literary genius. In Johnson and others of his day, those capacities owed more than a little to the arrival on the scene of a chemical substance: caffeine. And not just their capacities. Schmidt, a professor of English at Idaho State University, thinks the arrival of coffee and tea in Europe around 1650 had something to do with the birth of the Enlightenment.
Sleep in the pre-caffeine era was different in quantity and character. In 1630, a sermonizing John Donne told the king of England that sleep was "shaking hands with God," reflecting the general view that slumber opened the door to contact with the divine. Schmidt says that in the days before caffeine--and advances in lighting and mechanical clocks, which also came along in the mid-17th century--people slept for eight hours, often punctuated by a waking interval of an hour or so that established a more intimate connection to the world of spirits. …