Does your Aspie have trouble settling down to sleep, or staying asleep overnight? If so, you might want to ask your GP or paediatrician about Melatonin, a naturally occurring hormone produced in the pineal gland in the brain. Most people produce sufficient quantities to ensure regular sleeping patterns.
Melatonin works as part of the body's sleep-wake cycle, and is affected by light. As the day fades, and darkness increases, the body naturally increases melatonin levels, causing drowsiness and lowering body temperature. Exposure to light, particularly up close, inhibits this process, which is why you should turn off the PC well before bedtime!
Some studies are showing that individuals on the autism spectrum may not produce enough of this "hormone of darkness", thus resulting in poor sleep habits. Unfortunately there is no blood test for this at present, so a trial approach is required. If abnormally low levels of Melatonin are NOT the problem, you will quickly be able to tell. If they are, then you should see an immediate improvement.
While available over-the-counter in the US & Canada, in Australia & UK you will need a prescription. While some Australian health funds may provide rebates for it on top cover, there are no Medicare rebates.
Make a note to ask your doctor next time - it could be worth a discussion, at least.