HTC One X+ - beeping at 1:30am - why?

[DarkSarcasm]

Hi all,

I have a HTC One X+.

For the past couple of weeks, it has been randomly beeping at 1:30am. It sounds like it is the alarm going off but I don't have an alarm set for that time and the alarm I do have set has a different ringtone.

I have run AVG anti-virus app and it didn't find anything.

I have looked through my apps but can't think of anything that would cause this.

Has anyone else had this problem? I'm assuming I will have to do a factory reset but I'd like to avoid that if possible.

Thanks