In the northern countryside, kang is mostly built in the south of the bedroom, and the "edge of kang" is in the north. When you sleep, your head faces north.

If the kang is built in the north of the bedroom and the edge of the kang is in the south, you will sleep with your head facing south.

The kang in the east and west wing is also on the side of the kang.

If you sleep upside down, it's called "head in".