Sort of like Stevepit's idea or you could leave an anonymous note unless of course you're the only neighbor. You could also complain to the landlord if you are continually awakened by their over zealous activities. You only need to say that your neighbors are very noisy and constantly wake you up in the middle of the night. Keep a record of every-time you are awakened, so you have some type of verification to give the landlord. However, if it is only an occasional happening, as unpleasant as it may be, just deal with it.
if it annoys you enough start making really loud moaning noises and if they hear you they'll prolly get really embaressed and stop makin so much noise.
Same thing happened to me...and they went at it every night...I left a note on their door when I knew they were gone telling them that the walls (floors in my case, they lived below me) were very thin and unless they enjoyed having an audience every night, they might want to turn it down a notch or 3....The noise stopped lol.
You could mention to your neighbors that the walls must be a little thin and that you just wanted to let them know because you don't want to feel like you're eavesdropping on their personal moments. Complaining to the landlord isn't going to help as your neighbors have a right to have sex in their apartment. If after talking with your neighbors you notice excessive screaming... then I would mention the noise to the landlord. Unfortunately, sometimes this is just part of apartment living. I had a neighbor once that you could hear the bed squeaking over and over (and obviously I knew what was going on)... then I had to explain to my young son why the neighbors were allowed to jump on their bed. lol ~ I knew they had the right to enjoy their apartment and they couldn't help that I could hear... we just turned up the television a little bit because it wasn't worth the embarrassment to mention it. They moved out 6 months later and I didn't have this issue with anyone else during 7 years of apartment living.
Same thing happened to me...and they went at it every night...I left a note on their door when I knew they were gone telling them that the walls (floors in my case, they lived below me) were very thin and unless they enjoyed having an audience every night, they might want to turn it down a notch or 3....The noise stopped lol.