I hope stelingo is not doing that. But here is another thing for stelingo to note:PS I'm not helping you cheating with your HW or something, right?
My sentiment too. The former sounds broken to my ears. I think it is more of a colloquial usage. Then again, I would still inject a pause in between. "晚上十点前睡觉!? .... 不可能!".晚上十点前睡觉不可能 seems really awkward. I would say either 要在晚上十點前就上床睡覺是不可能的 or 不可能在晚上十點前就上床睡覺.
Note that is in Chinese is 是, therefore is impossible should be translated as 是不可能的.