sleeping on a tatami mat?

Can anyone tell me if a tatami mat on the floor is suitable for sleeping?
I really don't like how much room a bed takes up.

Can anyone tell me if a tatami mat on the floor is suitable for sleeping?

It is not suitable. Too hard!

I really don't like how much room a bed takes up.

Then, I recommend to use a futon that can be stored in the closet during the day, just like in the traditional Japanese way:
http://www.japan-guide.com/e/e2007.html

To use futon and store it in the closet is like this. View the scenes at 0:08 and 1:38.
http://www.youtube.com/watch?v=_xi07UoIKd8

And, I love napping on a tatami on summer time. Surface of tatami is cool at hot day. (Surface is not straw but igusa grass).

a single futon in Japan is roughly the size of 1 tatami mat.