I went into this with reasonable expectations. I had read the meta-analyses, I knew the evidence was modest, and I was prepared to give it the full 2-4 week trial period that everyone recommends. I purchased a reputable brand (Gaia Herbs) standardized to valerenic acids, took 600mg nightly 30 minutes before bed, and kept a sleep diary.
After 14 full nights of consistent use: nothing. Not a subtle improvement, not a slight edge taken off -- genuinely no perceptible change in sleep onset time, sleep duration, number of nighttime awakenings, or subjective sleep quality. My sleep diary numbers were virtually identical to the two weeks before I started.
I did get the famous vivid dreams on about 4-5 of the 14 nights. So the substance was clearly doing something physiologically. But whatever it was doing did not translate into better sleep for me. I also experienced mild nausea on about half the nights, particularly if I took it closer to bedtime rather than with a small snack.
I think valerian probably does work for some subset of people, and the clinical data supports a modest average effect. But the variability in response is enormous, and I appear to be a non-responder. If you are considering valerian, keep your expectations calibrated: it is a mild herbal supplement with modest evidence, not a reliable pharmaceutical intervention. Give it a fair trial, but do not be surprised if the answer is that it does not work for you.