magic fingers

I am not that technologically disinclined, but I have no idea how I manage to keep doing this in the middle of the night. Once again - and this is not a first - I managed to capture my screen. The first time I did this, it was my lock screen with my 4:00 am wake up call alarm ringing. This time, a set of texts with my mother. 

So, who can tell me how this is done?