My bedroom is in the South and its floor also slopes to the South. What should I do?
That is wrong; correct the slope first, because slope matters most. More important than treatments such as changing the sleeping zone is maintaining the slope of the room, which alone removes about 60 percent of the dosh.
Related questions
Why is a dying person laid with the feet toward the South?
So that life leaves the body quickly without getting stuck, because of the magnetic poles of the earth and the body. For the same reason a living person should never sleep with the feet toward the South; keep the head to the South instead.
Why is sleeping recommended in the South-West or the South?
Sleep is an activity of Saturn, and Saturn is a friend of Rahu-Ketu, who rule the South-West. The South is the seat of Yama, before whom no one prevails. Sun and Saturn are enemies, so sleeping in the East brings husband-wife quarrels; only a king-like person such as a politician or minister can sleep there. Applying this friend-enemy logic of the planets to every activity lets you derive remedies yourself.
Can asan (asana) wood be kept in the bed?
Yes. Asan wood is cheap, unlike sandalwood, and a whole bed can be made from it. If you have to sleep in a wrong zone, put asan wood under all four legs of the bed.
Do these effects, such as insomnia, apply to room doors, and does only the owner suffer?
They apply to the main door of the house, not to room doors. The people in whose name the house is and who invested in it feel the effects most, but other members can be affected too.
Does being manglik stop a person from sleeping in the South-West?
Manglik has nothing to do with it. It is considered only at marriage matching, when Mars sits in the 1st, 4th, 7th or 12th house, and Mars is power, not inauspicious. For the SW check whether Rahu-Ketu are debilitated, and for the South whether Mars is bad.
If a house faces South or West, must its slope also be toward the South-West, as in many houses?
There are two types of slope, which will be covered again. If water flows underground toward the South, it is not a big defect: electricity and water move underground everywhere without regard to direction, so an underground flow against the ideal direction does not create a dosh. People living where underground water flows to the South and West are also found to be happy.