Oh my...a thumb tack ! Never heard of anyone doing that for an anchor. Most of the pain anchor guys sleep on a marble or other small object. Its more of a dull pressure than actual pain. I also wouldn't recommend sleeping with an almond in your mouth. Sounds like that could be dangerous (choking). I use a visual anchor. I simply observe the darkness. Taping two fingers together is a good one Raph. I like that.