Decorating a one-room apartment is challenging.
A bedroom combined with a living room is often called a studio. It may or may not have a separate kitchen area. Sometimes the kitchen is simply a cubbyhole with small fridge, four-burner stove and microwave tucked in the corner of the room. Decorating a bedroom and living room together is a challenge to maintain privacy and still have room for guests and entertainment.
Double Duty
Every item in a small studio or combination bedroom and living room should do double duty. Storage is at a premium. Choose a desk that turns into a dining room table for two to four people. Or pick a table that has a drop leaf and can slide against a wall. The table is used as a desk and converts to a dining room table. Select a sofa that converts into a bed or use a futon. Test the mattress to make sure it's comfortable. A twin bed with a pleated underskirt and tailored bedspread is a sofa by day with pillows at the back and bed by night. Use hinged baskets as side tables.
Partition
No matter what you do to a queen size bed or double bed it's going to look like a bed. It's uncomfortable to have friends of the opposite sex over when the bed is always looming. Partition the bed so it's no longer visible from every place in the room. Place the bed at one end of the room away from the entry. Use a shoji Japanese screen, hanging curtains or even roll-up blinds from the ceiling to floor to hide the bedroom area. Partitions could be shutters, a folding screen or bookcases. Removable or adjustable partitions allow you to change the space for an airy look when you're at home by yourself.
Define by Color
Even small spaces still allow for different functions within the room. Dining, sleeping, office and entertaining spaces are differentiated through color while maintaining a cohesive look. The trick is to choose colors in the same shades. Your main color scheme might be