It's time you went to bed.
Mō neru jikan da zo.
now; soon; shortly; before long; presently; already; yet; by now; (not) anymore; further; more; again; another; the other; interjection used to strengthen expression of an emotion (often exasperation)
to lie down; to go to bed; to lie in bed; to sleep (lying down); to sleep (with someone, i.e. have intercourse); to lie idle
be; is; indicates past or completed action; indicates light imperative
(sentence end) adds force; indicates command