It makes no sense!

In the last 13 years that Chad has been in the navy, I've spent a lot, I mean, A LOT, of nights alone. I've never really had a problem sleeping without Chad there. It's not that I wouldn't prefer that he were there, it's just that I was never one of those women who had trouble sleeping when their husbands were gone. I felt very blessed for that since Chad was gone alot. BUT (you knew that had to be coming, right) since our moved here to Maine, I've started having trouble sleeping when he's gone. This makes no sense to me. How can I be perfectly fine sleeping without him for years and then all of a sudden struggle with it. The frustrating part is, he's only gone when he has duty, which is about every 9-10 days, so it's only one night here and there. So, why am I having trouble sleeping with him gone now? I never have liked duty days, but now that I'm sleep deprieved because of them, I like them even less.