I know a lot of moms with kids on the spectrum have troubles with getting them or keeping them asleep - just like I do - so I thought I'd share this.
My son is tired and ready for bed at 5 or 6 pm and the automatically wakes at 4 am or earlier EVERY SINGLE DAY. So after a long battle with this, I took him to see a sleep dr and he was diagnosed with having Advanced Sleep Phase Syndrome http://www.brightenyourlife.info/ch6.html
He was prescribed to use a light box from 5:30-6 pm daily and then to put him to bed later (8:30) to help his body get into a more natural rhythm. Right now, he naturally wants to sleep from 5-4 am and that is no bueno. He actually asks to go to bed right after dinner. The opposite can also happen - not being able to sleep until later than normal. Those individuals would use the light box in the morning to trigger their brains to understand that NOW is day time.
Also interesting, we've been giving him melatonin nightly and the dr things that for Gavin and someone with ASPS, we could actually be making his sleep worse.
I hope this is helpful or somewhat interesting. If it wasn't my situation, I would be intrigued.