Easiest would be to switch rooms and use another room as your bedroom, if possible.

If that's not possible, what I think you need to do is insulate the bedframe from the floor.

Get a large area rug and padding to go underneath--large enough so that your entire bed will fit on it. Get thick foam to put under the legs of your bed. Make sure the bedframe doesn't squeak--if it does, oil it or tighten screws or do whatever you need to to make it stop.

The long-term, most effective and most expensive solution is to put down a new floor, with a sound-dampening underlayer. I don't know if you own or rent, but you might be able to work something out with your parents if they own the building.

Thanks! Unfortunately, we can't switch bedrooms. A rug and padding sounds doable. What kind of foam should go under the legs? Our frame is definitely squeaky.. I was actually thinking that it might be easier just to put the boxspring and mattress on the floor (on the carpet, on the padding, etc). Any idea if that would work better than trying to fix the frame (it's old, and I don't know how much we'd be able to de-squeaky it).

I don't know much about sound-absorbing foam, other than that it exists. But they make it for use under stereo speakers, to help stop the noise from going to the floor below.

Or you could try felt--really thick felt, like an inch or more thick. Felt has great sound absorbing qualities and would probably hold up better under a bed. You can also get felt rug pads.

A new bare-bones metal bed frame will run you less than $100 for a queen size bed. It might be easier to buy one than to fix the one you have.

I don't know if putting the box spring directly on the floor would make things better or worse--you probably will have to experiment with that.

Also, you can try in general to keep as much sound in the bedroom as possible. The more fabric and other soft surfaces you have in a room, the more sound is absorbed and the less sound escapes the room. While your best bet is to concentrate on isolating the bed from the floor, adding curtains if you don't have them, and other fabric, like an upholstered chair or lots of cushions or a fabric wall hanging will help with noise overall. Even bookcases filled with books, not decorative objects, will help to keep noise confined to the room.

To start, I'd get a rug and the thickest rug pad you can find--go to an independent carpet store and tell them you need to soundproof the floor and ask what's available. You don't want those thin little rug pads with lots of little holes in them--they won't help at all. Add a new bed frame and see what the results are. I suspect that a rug, padding and a new bed frame will solve most of the problem. Just make sure the legs of the bed are on the rug/padding.

Nice response camlan. I agree with it completely

How are you going to sound proof a floor?