Afraid of the dark?

There was a time, many months ago now, that Aaron would sleep about 9-10 hours at a stretch, waking up for a feeding around 4am, then sleeping another 2 hours. But some time before his stomach bug, he was teething and starting to wake up around 2am, and sometimes again before he'd get up for the day. Then when he had the stomach bug, he was up 2-3 times at night, and I fed him each time to make sure he was rehydrated.

But now, he is still waking up 2-3 times after he goes to bed (although the first time is usually between 9-10pm, before I got to bed). He wakes up crying and I've tried to wait a couple of minutes to see if he'll go back to sleep, but he usually just gets louder. But we notice that in the morning, when he wakes up for the day, he can be awake for 30-40 minutes by himself in his crib, making noises and playing with his stuffed animals, but not crying. Sometimes, if he wakes up around 5:30, we just let him go and he usually goes back to sleep for another hour or so.

So why is he OK at 5:30 or 6:30am and not in the middle of the night? Although I usually nurse him to get him back to sleep, I don't think he is really hungry. So now I am wondering if he is afraid of the dark. Has anyone else had this experience? We are going to try putting a night light in his room to see if that helps.