I need help with a door bell

I made a very simple door bell
and installed it on the wall
It works very well until the middle of the night
then at about one oclock (Australian time)
It starts to click very slowly and then speed up
the clicking sonds a bit like when you turn a speaker on
and it clicks
I hope some one can help me

I think you got a ghost in your house :lol:

Well, jokes apart. The problem may be due to very slow charging of capacitor inside the bell due to leakage current that may be flowing in the circuit. The relation with one o'clock sounds just a co-incidence.
Please post the schematic so that we can help you find the exact cause.

Maybe energy remote signals coming in this time on mains and disturb it.
I agree with Kinjal, upload Your circuit for considerations.

Yes, that may be a cause too.