The dents appear on the thumbs, index and middle fingernails of both hands. I have experienced this in the past, many years ago and believe it is a sign of ill health. The dents look as if a new nail has grown under the original nail (about two weeks growth, I would say). I haven't been particularly well for a few months having turned to alcohol, but I have recently stopped drinking completely. My mother has also been very ill with spinal problems which may have added to the stress. Please advise if it stress related or due to alcoholism in the past.