“Head pressing is a condition characterized by the compulsive act of pressing the head against a wall or other object for no apparent reason“

Cats who are sleeping with their face down, this is normal cat behavior. Some cats are just most comfortable like this.

When it comes to head pressing, you will see your cat doing this against walls while sitting, and while awake. They will press their head up against something, unrelaxed.

Source (has pictures demonstrating this behaviour)

It doesn't seem to be the case for the pictures I've seen so far in this subreddit, but I thought it would be nice to let people know about this just in case.