Perhaps. Australian researchers asked 24 young adults to take naps of 5, 10, 20 and 30 minutes and then tracked various factors in the three hours after they awoke.
It turns out that a 5-minute nap is nearly useless in terms of fighting fatigue and boosting cognitive performance. The 20- and 30-minute naps had several benefits, but they didn't kick in immediately upon awaking; participants initially reported a brief period of impaired performance and alertness. The 10-minute nap, though, resulted in "immediate improvements in all outcome measures," according to researchers, and these benefits lasted just as long as those from a 30-minute nap.
Anecdotally, my experience supports the researchers' findings. A half-hour nap usually results in me setting my alarm for another 30 minutes, but I feel like a million bucks after a 10-minute nap. Do you nap during the day? What's your preferred nap length?