It might not be snoring that keeps investors in CNS Inc. (NASDAQ:CNXS) awake at night these days. Two patents on the company's top-selling Breathe Right nasal strips are being re-examined by the U.S. Patent and Trademark Office.

CNS almost completely owns the nasal strips market, with a 93% market share. Sales of Breathe Right products -- including the nasal strips, throat spray, and Vapor Shot! personal vaporizer -- accounted for 77%of the company's $87 million revenues for 2004. While the company has had challenges to its patents in the past, this time marks the first time the patent office has agreed to re-examine them.

Breathe Right strips are plastic bands embedded in an adhesive pad. They are placed across the bridge of the nose, which serves to widen the nasal passages, effectively allowing users to breathe more easily. Professional athletes have found them to be useful in helping them breathe easier while playing sports, though at least one study disputes that idea.

Despite being the market leader, CNS saw last quarter's Breathe Right sales falter, falling 5% with earnings down $0.05 a share from a year ago. It was on the strength of its incongruous FiberChoice supplement product that the company was able to ultimately beat analyst expectations by $0.05 a share.

The patent challenge is at the behest of Silver Eagle Labs, a company that CNS sued in February after accusing it of violating two nasal dilator patents it has held since 1996. The patents do provide a real barrier to entry to the market as witnessed by Schering-Plough's (NYSE:SGP) attempt a few years ago to market a competing product, only to limp away with its tail between its legs.

CNS was an early recommendation of Motley Fool Hidden Gems guest analyst Matt Richey. Investors were apparently not snoozing when news of the patent challenge hit, and they slapped the company down 8%, which ought to present an opportunity to pick up shares of a company sporting an enticing enterprise value-to-free cash flow (EV/FCF) of 10. Fool contributor Rich Smith views CNS as one of his gems for the taking.

The patents being challenged remain in effect unless and until the patent office changes its mind. Yet as this is the first time the Office has agreed to review the patents, it's a development investors should keep an eye on.

Fool contributor Rich Duprey wants to patent a home delivery service of Krispy Kreme doughnuts. He does not own any of the stocks mentioned in this article.