I've done that before [mainly because I have every-changing sleep patterns], I think it works, I don't remember what days I do that since I never write down my sleep pattern in my Dream journal to explain how I might have became lucid.

It usually happens on weekends since I don't hav emy alarm on, I can sleep in, and I'll wake up extremely early whether I want to or not for a bit [like 2:26 AM on a Saturday when I don't normally wake up until 5:30 so sleep in until 9 AM]. Lucky me that if I was asleep not too long ago [say 1-40 min ago] I can go back to sleep with little trouble.