I didn't get enough sleep last night.
我昨晚没睡够。

I feel sleepy, I had nightmare last night.
好困，昨晚做噩梦了。

I couldn't fall asleep.
昨晚睡不着。

I'm still sleepy.
我还困着呢!

I stayed up late last night.
昨晚我熬夜了。

I'm still drowsy.
我昏昏欲睡的。

I'm still yawning.
我还打哈欠呢。

I have a hangover.
昨天的酒还没醒呢。

I'm a night person.
我是个夜猫子。(早上起不来的意思)