Sometimes, slumbers.sleep, especially light sleep.
6.
a period of sleep, especially light sleep.
7.
a state of inactivity, quiescence, etc.
Origin: 1175–1225; (v.) Middle English slumeren, frequentative of slumen to doze, derivative of Old English slūma sleep (see -er6); compare German schlummern; (noun) Middle English slomur, slomber, derivative of the v.
mid-14c., alteration of slumeren (early 13c.), frequentative form of slumen "to doze," probably from O.E. sluma "light sleep" (cf. M.Du. slumen, Du. sluimeren, Ger. schlummern "to slumber"). Frequentative on the notion of "intermittent light sleep." The noun is attested from late 14c. Slumber party first