Favourable bed positions

A big hello to everybody on this site I've just discovered.
Another thing I'm rather new to in Feng Shui and I would really appreciate some tips on bed positions. My bed head is oriented east now and it feels ok, but we have a really small bedroom and I feel like rearanging a bit better. So I would like to know what you guys have to say about orienting the bed to the north (that is sleeping with our heads to the north).
And does the fact that the wall behind our bed head is the one with the entrance door to the bedroom?
We would be facing the window if we position the bed north-wise.
Anxiously waiting for your answers,
Gayetika.