My DD needs more sleep than average. This is not to say she was an easy sleeper as a baby. We did eventually sleeptrain (no rotten tomatoes, please--I was losing it and it worked quite quickly and well).We worked REALLY hard on establishing rhythms and we had strict bedtimes and naptimes. It sucked having to leave stuff early and be home (it actually isn't so great to be stuck home every day during nap) but if we were not strict about sleep, she was a nightmare. (Ha ha.)
DS has been an easier sleeper, but we have had issues with nightmares and fears. He has always done better when sleep-deprived than she does and has already dropped his nap (DD napped till mid-4).
I know this is another way these kids can be tough, but I do think the payoffs are worth it. There are mountains of research out there on the importance of sleep. Some people think some kids who "have" ADHD are mainly sleep-deprived. I also know a LOT of kids who are still not sleeping well at 6, 7, and 8 and they are definitely not all gifted...what they are is kids who have never really had a bedtime or learned to self-soothe. I am not at ALL saying everyone should CIO!!--but I do think it's important to keep trying and not just surrender to the whole "Well, the kid will sleep sometimes, right?" thing. DD would fight sleep like a maniac but man, she really needed it.