Pointing your foot at the door is a taboo in geomantic omen. Generally speaking, the orientation of the bed should be appropriate. When sleeping, don't point your feet at the door.
There are also some exquisite ones, even the shoes and toes put under the bed will not be placed outside, but inside.
From a scientific point of view, sleeping with your feet against the door is easy to get sick, and sleeping with your head against the door is easy to catch the wind.