We've had the same problem for so long!
DS used to amaze us by sleeping so little. He dropped both naps by 13 months, which was a torture for his caregiver. It took him forever to sleep, and he'd toss and turn he whole night (we all co-sleep). Funny thing was, waking up seemed like turning on a switch - sometimes he'd start talking even before his eyes were open.
Recently because of his 2e issues, I started sending him to a cranial osteopath. The osteopath examined him and gave me his prognosis out of earshot from DS - that DS has insufficient sleep and is unlikely to be sleeping at all. When I asked DS later, I was stunned. "Yes it's difficult to turn my brain off, so I go into deep relax and wait till morning." DS defines deep sleep as having dreams and "deep relax" as a state of deep relaxation with some awareness and no dreams.
In any case, we've been to several weekly sessions now at the osteopath, and together with a completely overhauled diet, DS is definitely dreaming again. He still finds it difficult to fall asleep, but at least he's clocking an average of 7-8 hours, and yes, it's actually hard to wake up him these days.
