A pillow's firmness level depends on the density of the pillow filling since more filling results in a firmer pillow. The type of filling material will also dictate the overall firmness of a pillow. The firmness of your pillow will affect the support and comfort you receive while sleeping. Pillow firmness levels are described as soft, medium and firm.
Soft pillows - Soft pillows are those with the least amount of filling or those filled using low-density materials, such as down or cotton. Soft pillows are ideal for those who sleep on their stomach or change positions often. This is because a soft pillow is relatively flat and this provides a shorter distance between the mattress and your head, thus reducing the angle of the neck. With a soft pillow, the chest, shoulders and neck are more correctly aligned and arching of the lower back is reduced.
Medium pillows - Medium pillows provide more filling and density than soft pillows, but less than firm pillows. Back sleepers benefit the most from medium pillows; the neck and head receives proper support, while the alignment and curvature of the upper back and shoulders is properly maintained. Medium pillows provide a balance of each of the qualities you receive from soft and firm pillows.
Firm pillows - Firm pillows provide the greatest amount and density of filling. Firm pillows are best suited to side sleepers. The increased pillow depth provides greater distance between the mattress and the head. The shoulders occupy this increased space the firm pillows fill the gap, providing an ideal horizontal alignment throughout the neck and spine. This type of pillow provides an added level of support to the head and neck.
The type of pillow you choose will depend on your sleeping habits and your personal preferences. If you change positions often throughout the night, or don't have a preferred sleep position, select a softer pillow that can be easily reshaped to accommodate each position. Natural filled pillows offer the greatest degree of flexibility. Firmer pillows provide more support and are effective for individuals who require additional neck and head support while sleeping. Choose your pillow carefully. The type of pillow you choose can greatly affect your quality of sleep.