- sleep (v.)
- Old English slæpan "to sleep" (class VII strong verb; past tense slep, past participle slæpen), from West Germanic *slæpanan (cf. Old Saxon slapan, Old Frisian slepa, Middle Dutch slapen, Dutch slapen, Old High German slafen, German schlafen, Gothic slepan "to sleep"), from PIE root *sleb- "to be weak, sleep" (cf. Old Church Slavonic slabu, Lithuanian silpnas "weak"), which is perhaps connected to the root of slack (adj.). Sleep with "do the sex act with" is in Old English.
Gif hwa fæmnan beswice unbeweddode, and hire mid slæpe ... [Laws of King Alfred, c.900]
Sleep around first attested 1928. Sleeping sickness as a specific African tropical disease is first recorded 1875. - sleep (n.)
- Old English slæp from the root of sleep (v.); cf. cognate Old Saxon slap, Old Frisian slep, Middle Dutch slæp, Dutch slaap, Old High German slaf, German Schlaf, Gothic sleps.
Personified in Latin as Somnus, in Greek as Hypnos (see somnolence). Figurative use for "repose of death" was in Old English; to put (an animal) to sleep "kill painlessly" is recorded from 1923 (a similar imagery underlies cemetery). Sleep deprivation attested from 1906. Sleep-walker "somnambulist" is attested from 1747. To be able to do something in (one's) sleep "easily" is recorded from 1953.