Tip for you.
Do not, wherever possible, allow any body part (particularly your head), to make contact with any corner, sharp object or tough surface if said body part is moving with any speed or force.
Let me elaborate.
If you are crawling speedily across your bedroom carpet toward the exit, keep your eyes fixed firmly on your destination, rather than becoming distracted by the hypnotic movement of your swinging arms. This should ensure you avoid driving the top of your head into the ajar door edge.