People often make the mistake of assuming that a pillow is as good as any other and that you can make do with whatever you find in store shelves. Not to say that you cannot find any quality pillows in stores since there obviously are, but you need to first choose pillows according to your sleep position as opposed to personal preferences. Read my pillow reviews from similar sleeping customers.
People that sleep on the back are already starting to fall into natural spine alignment, which means that the ideal pillow for them should properly hold the head level with the shoulders with support under the neck that allows the soft tissues to relax properly. The best support for back sleepers is provided by thinner and more contouring pillows.
Pillows that are either too soft or thin may permit the falling back of the head too far, while those that are too lofty or thick tend to shift the head forward, creating obstructions in the airways along with pressure points along the back of the head. Unfortunately, this poor posture tends to create stress through the shoulders and into the lower back.
People that sleep on the side have a very healthy position to be sleeping in, but need to take care to keep the weight and curves of the body properly supported to ensure proper spinal alignment.
Pillows are highly influential to side sleepers and thicker, gusseted, and more supportive pillows are usually worth considering to keep the head lifted and level between the shoulders, along with supporting the neck due to the gap left between the head and shoulders.
People that sleep on the stomach don’t always technically need a pillow because they have already elongated the spine through the length of their body. The issue with stomach sleeping is that no matter how much the body is supported, spinal alignment will almost always be compromised due to the turn of the neck and head, or even the end of the knee and hip to the side.
Stomach sleepers still need the comfort of a pillow and very thin and soft, contouring pillows can be ideal options for such people to help support the head and neck without the need to lift it too far. Stomach sleepers can support the upper body and shoulders or may even sleep in a stomach and side hybridized position to relieve stress off the lower back. Thin, soft pillows can help with that.