Graham it also adds to the very good bailiff's pleasure to let the poachers think they ain't been sussed.
Only ever happened once Phil when i was a kid i only discovered years later while chatting to the retired keeper that he knew i was there. The chap that got fined was a muppet advertising the fact he fished there with pictures of him and the fish.
Bite alarms imo are responsible for a lot of rods being left unattended, as are the silly transmitters that can tell an angler they have a bite while they are goodness knows how far away from their rods, its become accepted on some waters.
Sleeping while rods are fishing is something i have done but the longer the session is the more i became aware of any bleep of a buzzer even waking to things that sounded similar, all that's needed is a little common sense if you are so very tired that you desperately need sleep reel in.
To illustrate that my friend and i had returned to work after 10 days in the Netherlands, my friends job entailed walking round the factory checking different things, he often used to watch carp in the canal that ran through the factory and it was after doing this that his bleep went off which had him running back towards the canal so attuned to the sound of a buzzer had he become.