The bends are caused by dissolved nitrogen entering the bloodstream and moving into the soft tissues, then expanding, forming bubbles, when decompression takes place too quickly. As long as one is under pressure, there's no problem.
Nitrogen narcosis, on the other hand, happens while one is under compression. The nitrogen dissolved in the blood alters the way electricity is conducted in the brain, leading to loopiness. One source I read said that every fifty feet of depth is equivalent in its effects to one alcoholic drink, which led me to wonder a bit about those driven to dive.