Walk around your loft, and select a corner for your bed to go in. Ideally, it should be at an end of the loft away from communal areas like the space where the television is or the kitchen area.
Push your bed slowly over to that corner. It's important to place your bed in a corner as the two surrounding walls give you the two out of the four walls that you need for your makeshift sleeping quarters.
Measure the side of the bed that faces the rest of the living space. In front of that side of the bed, place a large bookcase that is at least 6 feet high and wide enough to block most of the view of the bed. The shelves of the bookcase should face out toward the rest of the loft, not toward the bed. Store your books, knick-knacks and decorative items on the shelves.
Place a decorative screen in front of the remaining exposed side of the bed. If this side isn't facing the rest of the loft, you can skip this step. However, if you truly want to feel like you have a proper bedroom, use the screen to create a sense of closure.