Chin straps are most effective for those who sleep with their mouths open, according to StopSnoringrx. If the person who snores is not an open-mouth sleeper or moves around a great deal causing the chin strap to fall off, the device may not be effective.
StopSnoringrx shares that when a person reaches the stage of deep REM sleep, muscles become relaxed. This can result in a relaxing of the jaw causing the mouth to open. There can also be a relaxing of the tongue, which causes the it to slide backward and block air passage to the back of the throat. This blockage causes the snoring sound. Using the chin strap in this situation keeps the jaw from relaxing into an open position and prevents the tongue from sliding backward.