Used both literally (e.g. 1 Sam. 3: 2 ff.) and also metaphorically for idleness (Prov. 24: 33 f.), spiritual laziness (Eph. 5: 14), or death (1 Cor. 15: 20, AV, RV, NRSV marg.).
Citation for sleep
Citation styles are based on the Chicago Manual of Style, 15th Ed., and the MLA Style Manual, 2nd Ed..
MLA
"sleep." In A Dictionary of the Bible. Ed. W. R. F. Browning. Oxford Biblical Studies Online. May 18, 2013. <http://www.oxfordbiblicalcstudies.com/article/opr/t94/e1781>.
Chicago
"sleep." In A Dictionary of the Bible. , edited by W. R. F. Browning. Oxford Biblical Studies Online, http://www.oxfordbiblicalcstudies.com/article/opr/t94/e1781 (accessed May 18, 2013).