Chiming in very late here, but I know many parents of gifted kids deal with sleep problems, so others might be searching...
I was advised by several doctors to try very low-dose Melatonin (300 mcg), which some studies have found to be more effective than higher dosages.
My gyn and PCP both advised me to take 300 mcg daily for 30 days, 2 hours before bed, to try to develop a better sleep pattern. My son's ped advised the same. Ds has used it intermittently (with amazing results), while I've used it more regularly.
I had previously tried 3 and 5 mg doses and found that I had very vivid dreams and didn't sleep as well. With the 300 mcg dose (I order on Amazon), I get perfect results.
Reviving this thread because a RL friend who uses melatonin for her kids was discussing an article aboul side effects in kids without giving specifics so I came back to reread here. I wanted to report that we switched DD (now 11) to the 300 mcg dose and it works really well. She doesn't fall asleep quite as quickly as she did on the 5 mg dose so we give it to her a bit earlier. She does fall asleep easily though and stays asleep. I think a bit less active in her sleep as well. I have not been able to find it in stores so also have to order from Amazon. On non school nights she usually skips it and usually stays up much, much later. So yeah, we are sticking with melatonin but are happy to be using the micro dose instead. Thank momtofour for letting me know about this option!