Some benefits of wearing a guard at night include prevention for the wearing down of teeth. As we grind or clench in the morning and night, microscopic layers of enamel are rubbed away and teeth eventually flatten, blunted, and more sensitive. Gum recession and deep triangular grooves in the sides of the teeth (abfraction) are also caused by grinding with teeth even cracking, chipping, and fracturing because of the continuous force of grinding.
Fig. abfraction from grinding where the gums have receded showing the roots of the teeth.
Constant muscle strain caused from grinding and clenching can also cause soreness with the muscles surrounding the jaw. These muscles connect to areas in the temples and toward the base of the skull, leading muscles in the neck. Many who grind may not know the reason for their headaches and neck aches, and may have disrupted sleep throughout the night, never feeling that they had a good night's rest.
You can purchase a night guard over the counter, but they do not protect the jaw joints or muscles, and may even make grinding worse by giving you something to chew on. A custom night guard can help with the straining of muscles from grinding leading to a better sleep.