Coil springs with non-linear loading responses and mattresses including the same

A coil spring, comprising:

• a continuous wire having a length and forming an upper end convolution, a lower end convolution opposite the upper end convolution, and a plurality of helical intermediate convolutions between the upper end convolution and the lower end convolution,
• the upper end convolution having a diameter, the lower end convolution having a diameter, and each of the plurality of helical intermediate convolutions having a respective diameter, and
• the continuous wire defining a pitch between each one of the plurality of helical intermediate convolutions, a pitch between the upper end convolution and the helical intermediate convolution adjacent the upper end convolution, and a pitch between the lower end convolution and the helical intermediate convolution adjacent the lower end convolution,
• wherein at least one of the pitches is different than another one of the pitches or at least one of the diameters is different from another one of the diameters such that the coil spring exhibits a non-linear loading response upon compression;
• wherein the plurality of helical intermediate convolutions comprises a first portion of helical intermediate convolutions having a first diameter and a second portion of helical intermediate convolutions having a second diameter;
• wherein the second diameter is less than the first diameter;
• wherein the first portion of helical intermediate convolutions comprises a first helical intermediate convolution, a third helical intermediate convolution, and a fifth helical intermediate convolution of the continuous wire, and wherein the second portion of helical intermediate convolutions comprises a second helical intermediate convolution and a fourth helical intermediate convolution of the continuous wire.