It's awesome your son has such an urge to read. Can you feed that urge earlier in the day...after school, before dinner, after dinner? Some kids just can't get enough of reading, no matter how much time they devote to it. My best friend growing up always had a book in hand. The trick is to still get the needed rest while feeding the enthusiasm for reading.
How many hours of sleep did your son average during the summer months? And what time did he usually go to bed, usually get up, etc.? Is your current school schedule quite different from that or pretty similar?
I know we let our son (almost 13) stay up later during the summer and he then would sleep-in each morning. When left to his own devices, he consistently slept 10-11 hours. The trick was to slowly work our way back to decent hours for school in increments, perhaps 1/2 hour each day. Then the last couple of mornings, we made sure he got up at a specific time, regardless of whether he wanted to sleep more or not. That way, he'd be more tired at night and have a better chance to falling asleep at a decent time.
I don't know if this helps your situation or not. The other responder had some good ideas as well. Create a routine that incorporates the desired reading and cozy time, stepping back from the number of hours you think your son needs. Often kids are more into the routine than the actual time on the clock and can be wooed into earlier bedtimes if you provide the desired pattern.
Another trick is to make sure your son is getting plenty of physical activity during the day so that he is literally tired. If his body is tired, his mind will likely follow suit.
Lastly, and I've never been good at this part, it might be a good lesson for him to experience being really tired once or twice to make the connection. Then talk about the connection, asking him what he thinks would be a better solution. (I usually want to impart my wisdom from my own mistakes onto my son rather than letting him learn his own lessons. So, instead of my son getting tired, he gets mad at me for enforcing his bedtime. But that's my cross to bear. : )
Celebrate your reader and help him work his schedule back so that he is getting the sleep that nourishes his body and soul. What soul wants to be cranky, anyway?!
P.S. Are you and your husband on the same page about bedtimes? We have a challenge in that regard in our family. Our son wants to spend time with Dad but he doesn't get home from work till 7ish. In order to get the quality time they want, the bedtime gets pushed later. I understand this emotionally, but practically, I have to deal with the emotional fallout if our son doesn't get enough sleep. So, sometimes there are mixed messages regarding bedtime in our household. Ah the joys of modern life!