I have a pair of quality night vision glasses, and I can say they are definitely not for metal detecting.
It's not that you can't see the ground, but they cause a weird sense of vertigo........or at least something similar to that.
You would also constantly be focusing them if you want to look at something close on the ground, versus something a few feet away.
Not only that, but they are surprisingly heavy. The weight of them to carry around in your hand isn't bad, but strap it to your head and you will know what I mean.
I would either go with red flashlight as suggested or an LED flashlight, but look from something (if possible) in the 2700 degree kelvin to 3000 degree kelvin range.
Anything higher than that, and it will look like a blue light out in the middle of a dark field.
If somebody approaches you at night and asks what you are doing, tell them you are looking for a shallow grave and would they mind helping............they don't stay long.