Can anyone tell me about sleeping arrangements for married Muslim couples?

Salam, yes a Muslim wife and husband sleep in the same bed if they please, that is the sunnah (way of the Prophet (sallahallahu alaihi wasalam)).

Muslim couples sleep on a bed, in a horizontal position on a mattress, usually with a special cushion known as a "pillow" which elevates their heads to be slightly higher than the rest of the body.

I hoe this has been enlightening.

Think about it...

Where do little Muslim babies come from if they don't?

Only if they're both men.

(runs away and hides in bombproof bunker).