As you can well imagine, there are some pretty significant concerns that come to mind when looking at #3 on that list; after all, R.E.M. sleep is vital to the bodys restorative process, and people who are chronically unable to achieve the R.E.M. state during sleep often experience an array of health problems, including emotional and psychological dysfunctions.
However, some anti-snoring drugs do try to limit the depths to which a snorer can enter the R.E.M. phase of sleep, thereby alleviating some of the deep, over-relaxation that occurs in the body; particularly in the throat area.
One of the reasons alcohol and sedatives promote and/or enhance snoring is because they over-relax the body (i.e. the body becomes relaxed beyond its optimal level; the last time you tried to wake up a drunk person should remind you of this basic fact of human biology). In the same way, some medications, to some degree, aim to prevent deep, deep R.E.M. sleep.
Some drugs are available over-the-counter; in particular, those designed to un-clog nasal passageways. These are typically designed for people suffering from a cold or flu, but some snorers find relief from using these decongestants and antihistamines.
Its also worth mentioning saline sprays, which are not drugs at all (its just salt water), but are often included in this category because theyre often found at drug stores. Saline sprays help keep the mucus membranes moist, and thus cut down on vibration by keeping the airway open and unclogged.