Ethanol or alcohol is a diuretic. This means that it inhibits a chemical called ADH (Anit-diuretic hormone) from being released from posterior pituitary gland in the brain.
Usually when this chemical ADH is released into the blood it tells the Kidneys to start re-absorbing more water. It does this by making the membrane walls of the collecting duct and the distal convoluted tubule more permeable, so water is absorbed back into the blood, conserving water. Leading to a concentrated small volume of urine.
So with alcohol being a diuretic, ADH is not released and so little water is re-absorbed into your blood, so you end up peeing out a large volume of diluted urine. This explains why you end up running to the bathroom every ten minutes!
This is not good because your body is losing more water than it should do, hence the reason for the horrible raging hangover in the morning, you’re simply dehydrated. Top tip for stopping the hangover, drink lots of water after a night out.