score:9
According to the description of events in medieval chronicles (namely the 14th century), no clothes at all were worn at night in Portugal. People really did sleep naked.
However, coifs might have been worn, though the chronicles do not mention them. This assumption of mine comes from images of the time, which sometimes (do note I say sometimes) show coifs worn by people in bed... even (or maybe especially) when those people were having sexual relations. On the other hand, most of these images are from non-Iberian sources so that the custom of wearing coifs to sleep may or may not have existed in Portugal.
Of course the people mentioned in the chronicles are nobles, with good beds, plenty of blankets and properly heated homes. People of lower standing might have slept with their clothes on for the simple goal of remaining warmer.
The chronicles in question are the ones by FernΓ£o Lopes. I've got them in book (there are plenty of editions around, though they're mostly old and partial). I recall in particular detail a chapter in the chronicle of King Dom Fernando, where a lady is killed by her 'secret husband' on suspicion of adultery. He enters her chamber at night and she gets up from the bed, hurrying to cover her nakedness with a chemise. Note that her nakedness is mentioned as something natural .
This passage is the one quoted by Portuguese historians to attest that medieval people slept naked.
Here's the link to download a pdf of a 19th century copy of the Chronicle of King Dom Fernando.
Upvote:7
There appears to be very little documentary evidence and quite a bit of debate on this. For example, see here.
The general consensus seems to be that they normally wore nothing, except sometimes a night cap. Picture evidence here.
Other commentators argue that they just as often wore a simple gown or smock, as argued here, without picture evidence.