Ok, my brain understands it now, thanks Amitabha. After having a look at the API for InterruptedException;
Thrown when a thread is waiting, sleeping, or otherwise paused for a long time and another thread interrupts it using the interrupt method in class Thread.
It seems that the only way for the piece of code where sleep() is called to throw an exception is if interrupt() is called on the thread that was executing when sleep() was called. Since no interrupt is called in the code, then we can assume no exception is thrown (I hope).