Why do people like to sleep with blanket over their face?

When I wake up and saw my friends or family member sleeping, I usually see them sleeping with blanket over their face. I hate doing that myself because it's suffocating and too warm to be comfortable. I always feel like I'm running out of air when I do that. Even my cat likes to sleep under blanket with me every night. I don't get it. Do you do that and like it, or don't you? If yes, then explain why you do that?