If you don't sleep with a pillow, you will feel dizzy, headache and congestion in your neck and back when you get up the next day. This is because if you don't sleep with a pillow, your head is lower than your heart and blood flows to your head, which will cause congestion in your head and produce the above symptoms. Choosing a pillow that conforms to human mechanics design is not only beneficial to the cervical spine, but also beneficial to the physiological bending of the whole spine and muscles beside the spine. The source of all diseases starts from the spine, and the spine can remain healthy forever. The function of the pillow is to ensure that the physiological curvature of the human neck does not deform during sleep.