My older cat Thumper has recently taken up door scratching as a new method of annoying me in the mornings. He started doing this after I returned from LA. Where he picked this up I have no idea since he never used to do it before. I have had to resort to putting him in the bathroom at night so he won’t wake up me and my wife in the mornings with the scratching. However he is consistant, he normally starts his scratching around 7am unless he happens to be really bored, then he tries it around 2am.