lt is time for sleep 这句话对吗

the grammer is not really correct,if you dont want to change your meaning, the answers should be:
best: it's time to sleep
or: it's time to go to sleep

these two are pretty common answer

是对的
SLEEP可以当名词用

这句话是可以的。
因为sleep既可以作动词使用，也可以作名词使用。跟study一样。。
for是介词，所以如果你将sleep作动词用的话，要先将动词改为动名词，即加ing.
可是如果你将sleep作名词用的话，就不用了。所以说，这句话是正确的，而且有多种说法。

不很对
sleep比较常用的是动词形式
应该说It is time to sleep
楼上说的两个例句也可以

yes or it's time went to sleep/bed.
it's time for you to go to bed.
it's time for sleep/sleeping.
it's time you should(don't miss out) go to sleep.

对.
同样可以说it's time to go to bed.或
it's time to go to sleep.