I know Daniela. TBH it is a very individual choice whether or not you want to do it. It is disputed in some countries and in others it is common practice. It is a fashion that comes and goes, as so many things in health education. Too extensive for this forum I think. But it is almost not possible to breast feed and NOT end up falling asleep with your baby feeding.
There is safe ways of sharing the bed with your baby and a mother has a very very sensible awareness as to what is happening around her, even when she is sleeping. You might remember that yourself. But again: this goes beyond the frame of this forum.
Here is a quite interesting article:
http://www.parentingscience.com/bed-sharing.html
and this one
http://www3.nd.edu/~jmckenn1/lab/overlaying.html
Just in case someone is interested in that topic
Hanna