8 yr/0 has JIA and says she can't get comfortable at night so she doesn't get any sleep. Any suggestions?

Hope This Helps... This is important because sleep deprivation makes the pain (and just about anything else) worse.First make sure she's taking her medications appropriately. No big meals at night.A warm bath before bed. No TV or computer in the bedroom.A comfortable mattress (maybe use that Tempur-Pedic memory foam).Form fitting pillow with good neck support.A heating pad, if needed. Loose, soft blanket.And kisses.
Treat arthritis well. I think the best way to manage this would be to treat the arthritis as best as possible. If there is ongoing pain and stiffness that is making her unable to sleep, maybe the arthritis isn't well enough treated at this point. You may also want to sit down and discuss what's on the child's mind. He or she may be upset about having arthritis, maybe a little depressed or anxious or insecure? .
Supportive. Warm bath with Epsom salts may be helpful as well as considering some massage and relaxing essential oils like Lavender.