This is a common problem, and I have been asked for advice many time, so I thought a blog post might be helpful.
Grinding your teeth (most often at nighttime) is called bruxism and, according to dentist friends, can seriously wear the teeth (more than eating, apparently) and you don’t want that. A quick scan of the literature reveals that for some people, the forces produced during bruxism exceeds the maximum voluntary force the same people were able to make during the day—and it is the larger forces that produce the increased wear.
I suggest wearing a dental splint at night, too, if you have any cracks in the molars (independent of bruxism) and the same suggestion even if you have perfect teeth, but grind them at night. The splint will stop the wear completely.
I made a short video on a range of exercises that can help decrease the ‘normal’ tension in the jaw muscles, thought to be the cause of bruxism. ‘Normal’ because though common in the statistical sense, not desirable. The video is found here:
Go really gently with these in the beginning; make sure you do all very slowly and with full attention on the sensations the first few times.
You may want to consider doing neck exercises too; there are a few on the YT channel. One theory is that undischarged neck tension is the main reason behind the grinding activity while we sleep. If everything gets looser (more relaxed) over time, that activity decreases. As well, the jaw is a gliding–sliding joint—so one’s bite (alignment of the lower and upper jaws) is purely a function of the balance of forces around the temporomandibular joint (TMJ). This joint is the last one in the chain of joints starting at the feet where any imbalance of forces can be resolved—if you have a skeletal leg-length difference, for example, then it is common to find jaw misalignment—but I suggest holding off on any bite restoration dentistry until the LLD is resolved (about half the population have a measured LLD of 5mm, or more; this is one of the core concepts in the book Overcome neck & back pain).
I say this because one of my teachers from many years ago had had about CAD $8,000 worth of realignment dentistry done when we met but she had not had her LLD looked into at all. When the LLD was partially corrected, the immediate effect in her body was that her jaw was no longer aligned and was very noticeable to her from a comfort and chewing perspective.
One more important aspect: reducing neck and jaw tension by itself makes people look younger; the reason is that tension in the facial muscles is the cause of wrinkles. On any of our workshops, by the end of the second day, the participants in the room are looking at everyone else’s face say things like, ‘Omigod: your face has changed!”, and so on. It’s amazing to see.
Last point: consider developing a conscious relaxation habit. There are immense health and wellbeing benefits (not to mention significant reduction in mental self-talk!). I have a bunch of free downloadable relaxation scripts on the forums. Put them on your iPhone, plug in ear-buds, lie down, and listen. You will experience amazing effects in the body over time, and this new habit will complement the jaw/neck exercises perfectly.