Or even 15 minutes (or 5!). (See Power Sleep, by James Maas http://www.amazon.com/Power-Sleep-Revolutionary-Prepares-Per..., or the Wikipedia page: http://en.wikipedia.org/wiki/Power_nap).

When you bike or take public transportation to work, you can't sneak a nap on your lunch break in your car. A nap room would be oh so helpful, and would dramatically aid productivity for sleepy employees benefiting from a power nap.