DS5.3 sounds a lot like your son. The only difference is the sleep. While DS needs sleep, he really cannot go to sleep on his own. Absolutely no naps because then he'd be up all night and even without naps and while being really tired, he needs Melatonin and Hydroxyzine and still can take anywhere between 1-5hrs to fall asleep at night. He needs some 12hrs of sleep to be himself but hardly ever gets it.
I know that a lot of the tiredness we see in DS is caused by Melatonin. It helps him fall asleep but it does NOT help him get enough good sleep and just makes him drowsy during the day. So we've been slowly cutting back on the dosage at the expense of him going to bed later and later.
We've also experimented a lot with Omega3 and it makes a huge difference for us. But the gummy ones are just too low dosage to make any difference in our boys. They both get this one in their almond milk (it's also great to hide in yogurt)
http://www.amazon.com/Barleans-Organic-Oils-Ultra-Potency/dp/B007R9TSSW/ref=pd_sim_hpc_1 ... it's makes our usually low verbal DS3.5 turn into a chatter box (when he's comfortable) and it gets DS5.3 be a very easy kid to manage, we have a lot less sensory problems, concentration problems. I ran out 2 days ago and waiting for new Amazon shipment and DS5.3 turned into a little maniac. Can't concentrate for 5 seconds, is angry, extremely sensitive, doesn't want to do anything at all. I can't wait for the UPS guy to get here so I can give him what his little body clearly needs! When we tried the gummy omegas it made no difference. The dosage was very low.
