D.Z.
My son grinds his teeth at night, too. Now he's 11 yrs. I'm not sure when it started, probably when he was six. Anyway, the dentist told me it was normal due to the jaw adjusting to the teeth. I was not consoled, but let it go. Some weeks are worse than others, his outward experiences seem to have any correlation. My husband wanted to give him a mouth guard (he is a lighter sleeper than I), but the dentist discouraged it... I would certainly look into allergies for the blinking. I'll have days when I have to blink a lot, it's very distracting for listening and remembering for myself. Good luck. I'll be interested in responses that had a successful turnout dealing with the grinding teeth.