I have been using eszopiclone near daily for like 4 months now. 4 mg per night, helps me sleep, but it only "helps", doesn't knock you out, you still have to "decide" to fall asleep and it helps you fall asleep faster if you do that.
Taking higher doses like 6 mg, 8 mg, 10 mg (max I've ever done) has no benefit, just makes me a little sleepy in the morning, does not increase sleep pressure.
I had to go on vacation for a week and tried diphenhydramine. I don't have any tolerance to it but I was pretty shocked, it induced sleep in me super fast, like 10 mins.
EDIT: OMG it has actually been 10 months, not 4. lol.