Did you get enough sleep last night?
Do you feel sleepy at work or in class?
Are you the kind of person who dreams a lot?
According to statistics, most adults need 7 to 9 hours a night for the best amount of sleep, although some people may need as few as 6 hours or as many as 10 hours of sleep each day. So which type matches your condition?
sleep in
I bet that a great number of people including you sleep in especially on weekends. Many people enjoy just staying in bed doing nothing, but not me.
"Sleep in" is a frequently used phrase to describe the phenomenon that people stay asleep in the morning for longer than they usually do. In Chinese, we say "睡懒觉".
hit the sack
This phrase is quite common. If you haven't heard or used it, you'd better take some notes.
sack本身是“麻袋”的意思，作为动词主要有“洗劫、开除”这两种意思。hit the sack 意为“睡觉”
据说，二战时期，美国士兵把睡袋叫做“sack”，“hit the sack”也就是去睡觉。
e.g. After a long journey, I'm wiped out. It's time for me to hit the sack. 经过漫长的旅程，我筋疲力尽了，该睡觉了。
联想记忆：hit the road 上路
doze off
Whether you are a student or an office worker, I suppose that you are familiar with（对...熟悉） this phrase as（因为） you do it every now and then（偶尔）.
e.g. Some students often doze off in class.
有些学生经常上课打瞌睡。
have a short doze
表示“回笼觉”，早晨按掉闹铃后再睡一会儿。
I do this a lot. How about you?
sleep like a log
If you know the word "log", I think you must know the meaning of this phrase. "log" 意为"伐木"，当然也很沉啦。所以你应该猜出这个短语的意思了吧？见下图，睡得很沉。
也可以说 a sound sleeper/ a heavy sleeper