Help to stop grinding teeth at night - can biofeedback or something similar effective?

Yes, electromyogram. Biofeedback is effective for bruxism. In addition to in-office training, there are simple, portable EMG units that can be used at night to interrupt the habit of clenching and grinding. Find a certified biofeedback professional at www.Bcia.Org or www.Aapb.Org.
You can try... I have heard of biofeedback in this regard. I am unaware if it is very effective. During sleep we are not in control of what we do. It seems to me with biofeedback we exercise some level of control to effect a change; during sleep I have my doubts that biofeedback makes sense to stop grinding....