1) Obviously, 잠 is simply the -(으)ㅁ noun form of 자다. Right? Yes, you are right. 잠을 자다 is also used. "잠을 좀 자야 해" 2) 잠들다 means "to enter sleep" or more naturally "to fall asleep". There is no particle attached to 잠, but could you have 잠을 들다 with sleep as an object? Or 잠이 들다 where "sleep enters"? 잠이 들다 will be better. 잠을 들다 sounds a bit odd, however, you can say 잠에 빠지다. 3) 잠이 깨다 means "to break sleep" or more naturally "to wake up". Now, here we have a subject particle, so "sleep breaks". You would never have 잠을 깨다, right? Yes, you can us e잠이 깨다, 잠을 깨다, or differently, 일어나다 ( get up) and 눈을 뜨다 (open eyes) 4) 자다 means "to sleep". Can it mean "to go to sleep" or "to fall asleep" too? Or does it mean something like... 잠 하고 있는 중이에요 (I am in the middle of doing sleep) Is it like the state of sleeping? 자다 means 'to go to sleep, to fall asleep or sleep or being in bed. But we don't say 잠 하고 있는 중이에요, we say 잠을 자는 중이에요. 잠 자고 있어요 or 잠들었어요. meaning 'the state so sleeping' 5) Are either of the following possible to mean "to go to sleep"? 자러 가다 = to go in order to sleep 침대에 가다 = to go to bed 침대에 가다 means to go to the bed to do something. But 침대로 가서 자라. means go to bed. We don't say 침대에 가다 instead, we say 침대에 눕다 (lie down on the bed) 침대에 눕다 sometimes means to have a rest as well. 6) Am I using the particles for "to/at" correctly in these sentences? 침대에 잠들었어요. 침대에서 자고 있어요. Yes you can use but 침대에서 잠들었어요 is correct. '에서' should be used such cases referring 'place' 방에서 자고 있어요. 의자/책상에서 자고 있어요 (meaning sitting on a chair sleeping) 차에서 자고 있어요 (sleeping in a car)