Sleep like a top

To sleep like a top means to sleep soundly and is an odd expression because children’s tops or spinning toys are hardly so stationary as to seem an apt simile for being sound asleep. The OED, however, gives a meaning for top as a “type of sound sleeper, in reference to the apparent stillness of a spinning top when its axis of rotation is vertical” and dates this meaning of top from 1619. The first citation, however, for the expression ‘sleep like a top’ appears later in 1693, in The Old Batchelour by William Congreve, “Should he seem to rouse, ‘tis but well lashing him, and he will sleep like a top.” The OED’s meaning of top as a type of sound sleeper now appears to be obsolete and it would seem that Congreve’s simile has replaced it.