Is it better to put the ceiling lamp in the middle of the room or try to avoid leaning to the upper side of the bed?

It depends on whether your bed is in the middle. Try to avoid putting the lamp above the bed. Lamp press is not good in geomantic omen. If your bed is not in the middle, then the light should be installed in the middle of the room. If your bed is to be placed in the middle, don't install the lamps in the middle. Besides, if you don't believe in Feng Shui, it doesn't matter where the lamp is installed.