I have this problem, but it only seems to appear in the morning about the time I need to get up.
I'm not jealous about much of anything -- someone's house, car, bank account, wife, etc. For the most part, I couldn't care less. But I AM insanely jealous of people who can rise out of bed early and still feel well rested. I hunt down and torture people that say they're morning people (by having them listen to me tell them what I said in this paragraph!!).