Genetic tools are providing promising results regarding the molecular mechanism of anesthetic action. For example, researchers can alter specific protein function and then determine whether this protein can be linked to sensitivity or resistance to anesthetic action in lower organisms. These approaches identify what proteins are involved in anesthetic action and can be thought of as a way to better define relevant anesthetic targets, which investigators can then focus on for structural studies. Other approaches, including sophisticated structural modeling of anesthetic binding to protein targets in a lipid environment and detailed structural determinations of anesthetic binding to soluble proteins, are also showing promise in further revealing the how of anesthetic action at the molecular level.
Thus the simple answer to the question "How does anesthesia work?" is that, although we know a great deal about the physiologic effects and macroscopic sites of action, we don't yet know the molecular mechanism(s) of action for general anesthetics. Many of the tools necessary to answer these questions now exist and we can look forward to new insights into how this great boon to humanity works at the molecular level.