I'm probably asking a stupid question that has an obvious answer, but I wanted to ask anyway.

Why is it that on some nights I can sleep 7 - 8 hours when taking Lunesta and other times when taking Lunesta I don't sleep through the night? How come that is?

My guess is that you're fighting sleep on the nights it doesn't work.

I found that I developed a tolerance to sleeping medications if I took them dailly for more than 3 or 4 days in a row.

That is not to say that they failed to help me sleep after 3 or 4 days, but rather that their effectiveness was starting to diminish.

The way I found around that was to rotate the medication I would choose to take. For example, if I was taking Lunesta for 4 days or so, I would take a break from it and then the on the first night I was away from it I would take the OTC drug Benedryl, or another sleeping aid that I had on hand.

This was done only after checking with my Dr first to make sure that it was OK with him.

Well I get better sleep on the medications than off. When I'm off them I'm up till 2 or 3 in the morning. That would be 3 - 4 hours of sleep approx. At least with lunesta, I get to sleep right away (within a few min), and I sleep till 4 or 5 (the nights it doesn't last long enough). That's about 6 - 7 hours. Both scenarios I'm in bed @ 10pm. There may be a chance I'm tolerant but some nights I get to sleep and sleep though the night (like last night) and other nights I get up a bit earlier.