Tsk, this is not good thumbs, it is in fact very dangerous. Being of a teenyish disposition like myself, you may well slip under the water! You could be having the water too hot as well, which may make you sleepy. Next time, take an alarm clock or an egg timer in or get someone else in the house to bang on the door very loudly after 15 minutes or so (you don't want to stay in any longer than that anyway, it's bad for your skin).
Hope this helps petal :)