Sorry. My fault for not mentioning this. The @ SLEEP instruction puts it to sleep forever until a watchdog timeout, or an interrupt wakes it up.

When it wakes up due to watchdog timer timeout, it executes the instruction immediately after the @ SLEEP, and lands on your goto cycle.

Any time you use the assembler version @ SLEEP you'll need to make sure you have WDT disabled unless you want it to wake up with the watchdog timer timeout.