It helps me sleep the vast majority of the time. The only times it disturbs my sleep, it's from a secondary action, not the actual kava buzz. That is, sometimes I get so uncomfortably bloated from it in the middle of the night, that my body tries to wake up...but I'm simultaneously heavily sedated from the kava which gets me stuck in the very uncomfortable nether world.
Waking up to pee is the other nuisance/secondary effect, but kava keeps me so sedated all night, that I fall immediately back to sleep most of the time. I wake up to pee no matter what, sober, alcohol, kava...but kava has been the only one that allows me to fall right back to sleep. I do feel like my kava sleep would feel more restful, if I could sleep through the night without ever waking though.
I'm not a heavy sleeper by nature and even when I used to drink alcohol, no matter how much, it never helped me sleep good...I couldn't sleep in late, I'd wake up in the middle of the night and struggle to get back to sleep.
Kava sleep is a godsend to me and it's one of the main things that kept me coming back to kava, I used to barely even get any effects from kava but still persisted with it almost entirely for the sleep benefits.
I'd say it absolutely helps but has the ability to hinder in certain circumstances.