This is actually about bedding. I started this when I moved apartments in college and lacked bedding. Back in highschool I had some back problems due to a bad mattress and slept on the floor for about 3 months. At the time I'd found this reasonably comfortable, so, lacking bedding, I figured I'd just sleep on the floor.
Okay, so you'd be surprised how comfortable this is actually when you get used to it. I have a friend who has been doing this for years actually and it works great for him. For me though I found that the bones in my hip and but slowly got more and more sore from pressing against hardwood. It's okay for a while, but I wouldn't choose this given other options
This is quite comfortable. Most carpeting is a bit pilly and will scratch a bit, so it's FAR more comfortable with a sheet. This was a more recent experiment actually, after I moved out to California to start my new job I didn't have a bed, so I slept on the floor for about 4 months. I have oddly broad shoulders and I tend to sleep on my side or sort-of twisted half front/side. I used to sleep on my back, but discovered it made post-nasal drip worse, which is a big issue for me in combination with my asthma. Anyway, I gave up on this because of my arm. I found that my arm was falling asleep pretty regularly, and it felt like I might be doing permenant damage to the socket and tendons by affectively dislocating my arm many nights. This was pretty okay, but I decided to save my shoulder and get something a little more padded
An interesting question to ask yourself is always "why do we do things this way?". In this case when I got my hands on a futon mattress with no frame I asked "Why do we normally put our beds off of the floor". It turns out that traditionally this was done in europe to discourage bugs from entering the bed, and so that rats/mice scurying across the floor would go under rather than over the bed. These are pretty good reasons, and even relevent if your apt is a bit sketchy (I had a friend who had termites and was very unhappy with being on the floor). In general though these issues are pretty much moot these days (at least for me). The other advantage of being off the ground is storage. I don't own all that much stuff though, so this didn't matter to me. Overall I LOVED sleeping on a mattress on the floor. So much so that I was given a frame and rejected it, it made my room feel significantly smaller, and I couldn't lie half-on half-off of my bed.
Well, recently I got a normal futon (after sleeping on the floor for a while). Really I still feel like the floor was preferrable. There are some advantages to being on a frame though. This way I can make it into a couch if I throw a larg'ish party at my apt. I am very short on seating, so this is a good reason. As a bonus I hear that futon frames have some kinky uses, though I haven't gotten an opportunity to test this out just yet.
Other people. If you hope to have other people sleep in your bed it is helpful to have it be "comfortable". My last girlfriend was okay with a futon on the floor, but would've vaguely preferred a slightly more cushy bed. She was pretty happy if I just used soft sheets though. Some girls may be creeped out by weird sleeping arrangements. Honestly these girls probably aren't very interesting to me aanyway, but if someone has a back problem, or join issues, or just can't sleep well on a less comfortable bed, it's going to be harder to get them to come over.
By mbrewer