Yes, bruxism(teeth grinding) can lead to jaw pain and headaches, especially in the morning time. A mouth guard is very useful for many reasons.one of the most important is that it prevents your teeth from getting smaller and smaller because of the grinding(causing a lot of damage to your appearance and your mouth's functionality+if you do it long enough, your pulp could be exposed or best case scenario, u'll suffer from toothaches). Another reason, and the most important one if you ask me, is that it helps your tmj(temporomandibular joint-trust me, you don't want to have problems with your tmj-i have them, i grind my teeth too).using the mouth guard may improve your simptoms or eliminate them, but you have to find out what the cause of your grinding is.It's usually because of stress associated with an occlusal dysfunction (your biting pattern is wrong). I postponed getting one myself and now i regret it a lot.my canines have no cusps anymore and a lot of my teeth are worn out+they have a higher than normal degree of mobility.Some of my friends used them and got rid of this "habbit".it shouldn't take a long time to get used to(i had one that was not for grinding-i wore it after i had my braces taken off- and i was ok with it) and it won't affect your sleep.if your dentist says you should get it, do it.cheers! :) PS: you should really look for the cause instead of dealing with the effect alone
5th year student in dental school.