Assess the bed frame. Check for loose parts and loose screws. Tighten screws, bolts and hooks to ensure that loose fittings don't create noise when you toss and turn in bed.
Spray lubricant all over the bed frame, fittings and metal parts that rub together. Doing so lessens the noise caused by friction of the bed's parts.
Check whether or not the bed sits level. Sometimes an uneven frame can make a bed noisy. If the bed's legs don't seem level with each other, push a rubber stopper underneath as many legs as necessary to create a solid surface for the bed.
Flip the mattress, and turn it in the opposite direction from which it has sat. Sometimes a noise can be caused by a mattress sitting in the wrong spot. A mattress should be flipped twice each year to ensure its even wear and to prevent squeaks.