"Well, my new age inclined mother has sent me some sort of earthing device as a Christmas present. Is it OK to experiment myself with it or should I just say thank you and put it away in a drawer with the other new age gifts she sends which I know are against Church teaching and will never use? (I have had many conversations with her in the past about new age practices etc. which are at the least bunk and at worst spiritually harmful and she simply refuses to listen to reason.)"
Earthing is not dangerous to your health because it doesn't do anything at all - good or bad. Why? Because it's a bunch of hooey and hooey tends to be harmless (except for the negative effect it has on wallets.)
Sadly, I must say the same about the earthing bands that your mom sent you. These too were a terrible waste of money.
For those who have never heard of them, earthing bands are elasticized bands that have conductive fibers on the inside that allegedy "ground the body" via an elaborate grounding system that enables people to connect to the earth's energy even when they are unable to make contact with it (walking barefoot, sitting on the ground, etc.). The bands are worn around areas of the body that need healing - stiff neck, sore back, etc.
It's based on the unsubstantiated theory that we can reconnect to the Earth's energy system just by standing barefoot on the earth, thus rebalancing our own bodily electrical system.
As this website explains, grounding products such as earthing bands are "barefoot substitutes" that utilize the ground port of a standard home outlet which allows electrons from the earth to pass through the ground wire and into the person touching the products.
A band kit such as the one DF received runs about $30. Earthing sleep systems which consists of sheets and grounding systems run around $200 and mats go for $60.
When you look at these products on the various websites, it's easy to see how people get pulled into these schemes. Proponents claim earthing does everything from improving blood pressure to reducing pain and increasing energy levels. The only problem is that there are no studies to prove any of these claims. Even though almost all of the websites I visited claim they have research to back up their claims, all of this research is either too biased to be considered scientific (they were conducted or funded by proponents of earthing) or are methodologically flawed (the structure of their testing was skewed toward a certain result or the sample size was too small, etc.).
We need to pray for DF's mom: first, that whatever she is seeking that makes her turn to the New Age she will soon find in Jesus Christ and; second, that she'll stop wasting her money on useless gadgets.