Do I need to adjust lighting?

I'm new to keeping dragons. Stilgar is a few months old(not sure precisely). I currently have him set up with a 13.5 hour "day", from 8am to 9:30pm. However, I have noticed that at around the 12 hour mark he frequently calls it a day. He chooses a hide(sometimes the one on the cool side, sometimes warm side) and passes out. If I take him out at this point he finds a fold of fabric in my shirt or a blanket and goes right back to sleep. During the rest of the day he is alert, curious, poops regularly and seems to be eating well.

He lives in my room, where it remains generally dark until his light comes on, but some light filters in starting at sunrise around 6am.

Is this normal, or should I shift his 'sunrise' forward, or even shorten his day? I'm concerned I could be stressing him out if the 'day' I am providing him is out of sync with his circadian rhythm. I certainly wouldn't enjoy trying to sleep with a spotlight on. Thank you for any advice and for reading this far!

That sounds pretty good. It's common for them to fall asleep early like that but it's OK. Just let him sleep if he's tired. A 12-14hr day cycle is about right. As long as you are fairly consistent with the times for the lighting, they will adjust to a schedule that fits yours so you can tweak it however you'd like but just try to be consistent.

Thanks for the info! Yeah, the hours are very consistent since I've got the lights on a timer, guess he's just been tiring himself out early haha.

My lights stay on a 16 hour photoperiod year round. My mob often take siestas.

Better off having longer than needed , than not long enough.