I remember postgraduate students passing out and getting very irritable during Ramadan. Some of them do go without water, whether or not it says so. There's no standard guidance, but I do remember one pregnant lady (who was entitled to lay the rules aside)trying to follow a strict regime - rather foolishly it seems to me.

Apparently for those living near or above the Arctic circle there are special rules as in summer of course, the sun never sets.

From the outside, it reads as if the rules were set up for countries where the day and night lengths are more even.

Paws