I did not start taking valerian for sleep. I have always been fascinated by dreams and lucid dreaming, and I read on several forums that valerian root was one of the most reliable legal substances for enhancing dream vividness and recall. I decided to experiment.
I started with 400mg of a standardized extract taken about an hour before bed. The first night, nothing unusual. The second night, I had one of the most extraordinary dreams of my life -- a detailed, coherent narrative involving traveling through an impossible city where the architecture folded in on itself. I remembered every detail upon waking. I could have written a short story from it.
Over the next month, the dream enhancement was the most consistent and noticeable effect. On roughly 4 out of 7 nights, my dreams were noticeably more vivid, more narratively complex, and much easier to recall in the morning. I started keeping a dream journal for the first time in my life because the content was genuinely interesting enough to document.
I also achieved lucid dreaming (becoming aware that I was dreaming while still in the dream) on three occasions during that month -- more than I had achieved in the previous year of trying various techniques. The dreams seemed to have a particular quality of detail and stability that made it easier to notice the dream state.
As a sleep aid, valerian was fine but unremarkable for me. I already sleep well. I noticed perhaps slightly faster sleep onset, but nothing dramatic. The real value for me has been purely in the dream domain. I continue to take it 4-5 nights per week specifically for this purpose.
One odd observation: on the nights when the dreams are most vivid, I sometimes wake up feeling like I have been busy all night. Not tired exactly, but like my brain was working hard. This passes within 15 minutes of getting up.