The basic premise of anti-snoring chin straps is that by holding the jaw closed the tongue is pulled upwards and forward, thereby providing a clearer breathing passage. Figure 1 shows a natural resting position of the tongue when the jaw is closed. Figure 2 shows a natural resting position of the tongue when the jaw is open. When the jaw is open, the tongue slides backward and downwards and thickens somewhat and there is less room at the back of the throat for the passage of air. In less extreme cases, narrowing of the breathing passage might result in vibrations of the throat or tongue as air passes by, thereby causing snoring. But in more extreme cases the tongue might actually come into contact with the back of the throat, as is shown in Figure 3, and block the passage of air, thereby producing obstructive sleep apnea. Hence, snoring is often a sleep apnea symptom, or it may be an indicator that one may eventually come to suffer from sleep apnea.
It should also be noted that snoring may be the result of vibrations in other portions of the breathing passage as well, such as in the sinuses. Furthermore, it should be noted that snoring or sleep apnea caused by a narrowing of the throat may not be caused by the tongue or tongue position. For instance, a narrowing of the breathing passage may be caused by the weight of neck fat producing a collapse of the throat passage when the muscles are relaxed during sleep. For cases such as that shown in Figure 2 where there is a narrowing or obstruction of the breathing passage due to open-mouth breathing, wearing an effective anti-snoring chin strap may lessen or completely cure snoring or be an effective sleep apnea treatment.