The Full (sometimes called Double), size mattress is 53 inches wide, which will leave couples only 27 inches of personal space. Both twin and full sizes are approximately 75 inches long, which still might not be tall enough for some adults.
A full size memory foam mattress is only ideal for a single sleeper, and only if the person is under 5 feet tall. This bedding option is usually a good mattress for teenagers to sleep on and more affordable. Parents have even started purchasing full size mattresses for their younger children, too.