The choice of bed
1, the inner layer with natural latex material elasticity is the best, but more expensive.
2, personally try to lie, see whether the mattress can support back, waist and buttocks. When lying flat, the waist is not hanging, shoulder pressure.
3, Size: Sleep on it, single bed length to the head and foot distance from the bed edge of at least 10 cm, the width of the body around the side edge of the bed about 20 centimeters. The double bed proposal ibid., but with the sleeping person need to have more than 20 centimeters of space.