I have basically the same thing, maybe a little less marked. Nap are pointless for me unless they last at least 90 minutes, because I'll spend the first half hour or so barely dozing. I can sometimes fall asleep more quickly, though, when extremely tired. ETA I have never fallen asleep by accident (once or twice I've noticed dozy sensations creeping up on me, but it's quite rare), and I'm an extremely light sleeper.