There is such a thing as too much of a good thing. These pharmaceuticals were originally based off valerian root, which works too, and is cheaper, and easy to obtain. You can always try going back to the roots. I find it helps me sleep every now and then.
I'm not a big believer in valerian, based on my experience. It's certainly not a stand-in when it comes to treating panic attacks. For sleep, it could work but I generally tend to prefer melatonin.