What are the reasons to use the toilet continually at night?

Hard to say: Some women have 'weak' bladders, that can only hold a smaller volume of liquid before needing to empty, sometimes if women don't empty their bladders often they can have leakage of urine which is a strong incentive to empty their bladder often. Some women have 'overactive' bladders where the muscle wall of the bladder contracts making them feel need to pee often. Caffeinated drinks make u pee more.