its very easy to question every aspect of your life up until you became sick, I am sure we all have done, and still do, I know I do...but I really doubt shopping at 9pm or going to bed at midnight was any major factor in the process. We have to remember that the majority of the world go to bed at midnight if not later, are physically and mentally active way after 9pm, and a very tiny amount get AF. Probably something like 000000.1 percent of the worlds population!
So dont beat yourself up in thinking what caused it, hindsight is one royal MOFO!!!! :)