Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Select Comfort (NASDAQ:SCSS), a retailer of mattresses and other sleep-related products, dipped as much as 10% after reporting disappointing second-quarter results.

So what: There won't be any sound sleep for shareholders today after Select Comfort reported a 1% increase in sales, to $207.4 million, and a 42% decline in income, to just $0.18 per share. Comparatively, Wall Street had been forecasting sales of $210.7 million, and EPS of $0.24. The company did reaffirm its full-year outlook, which likely saved it from a huge fall, but a 6% decline in same-store sales is hard for investors to ignore. The big knock against its bottom line was a 65% increase in expenditures due to new investments in technology and product innovation in its stores.

Now what: For the past year and then some, earnings season has been a big disappointment for much of the mattress and sleep-products sector. These companies are wholly dependent on consumer discretionary spending to drive their sales, and there's no guarantee that spending heavily on marketing will provide any meaningful differentiation between one company and another. Even with Select Comfort backing its full-year forecast, I'm not so sure it's an intriguing value even at 15 times forward earnings. For now, I'd suggest keeping one eye open, and monitoring this stock for a few more quarters.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.