Water noise wakes me up

I have moved into an art-deco building somewhere in the North Shore and my problem starts at 1:30AM when my upstairs neighbour goes and have a shower. Due to the fact the building is old plus the bathroom is located next to main bedroom, I keep on getting woken up EVERY night (or should that be morning!). The water works happens nightly and lasts between 30-40mins. I am at my wits end on how to solve this problem and hesitant to confront the neigbours as I live by myself and below them which means they can make my life worst – if you know what I mean.

Would really appreciate some advice on how to deal with problem as I have another 8mths to go on my lease contract.