Sofa bed

A sofa bed or sofa-bed (in the US often called a sofabed, hide-a-bed, bed-couch, sleeper-sofa, or pullout sofa) is typically a sofa or couch that, underneath its seating cushions, hides a metal frame and thin mattress that can be unfolded or opened up to make a bed. A western-style futon differs from a sofabed, although sofa beds using futon mattresses are common.
The far more portable camp bed is much older.
History.
Leonard C. Bailey took out a patent for making the first "folding bed" on 18 July 1899. The metal bed frame was capable of being folded, bent mattress closed for use if needed. Later, it was known as a "hide-a-bed".
William Lawrence Murphy took out a patent for making "In-A-Dor bed", which is known as a “Murphy bed” today. It is characterized with the folded space-saver into a wall-closet.
In 1931, Bernard Castro made and sold the "Castro convertible" by using $400 from his savings. Castro’s design is considered to be the evolution of most sofa beds sold nowadays.
After mimicking the Japanese founders, the futon appeared in the United States around 1980. William Brouwer is the person who evolved the first sofa convertible frame style in the United States.
Mattress types.
Although most sofa beds use a queen short mattress measuring 60" × 72", other common sizes include 58" × 72", 54" × 72", and 52" × 72". The average sofa bed mattress thickness is 4.5", thus being half as thick as a good standard mattress. Sofa mattresses can be produced out of many different materials, the majority on the market being made of springs or foam.
Spring sofa mattress.
Although springs can make a satisfactory sofa bed mattress, the following aspects have to be considered regarding a spring sofa mattress:
Foam sofa mattress.
Quality foam sofa bed mattresses compress as needed, the foam acting like an infinite number of springs. A high quality foam gives better support, molds to the body and snaps back to shape. Consider the following factors of a high quality sofa bed mattress:
Pocket-coil mattress.
Pocket-coil mattresses are generally higher in quality than spring or foam mattresses. Each coil is encased in its own pocket, allowing the mattress to keep its shape over time while also providing more sleep support. Pocket-coil mattresses are thicker than standard sofa bed mattresses, starting from 7" and going up to 10" for a premium product. The high-quality support provided eliminates the need for extra cushioning, allowing the mattress to become the seat of the sofa. This has resulted in a new style of sofa bed that does not require its mattress to be folded up and tucked inside.