Afraid of the dark?

Are any of your babies afraid of the dark? In the past week my daughter will NOT sleep in her crib. The second you put her down she cries uncontrollably, and she's never done this before. Last night was the worst, with multiple wakeups and she wouldn't sleep unless she was held. She could be sound asleep on me and the second I stand up to put her in the crib her eyes shoot open and she clings to me and starts crying. She even did it for her afternoon nap yesterday! Letting her cry doesn't do anything, clearly something is going on. We've tried sitting in and even sleeping in her room but she does the same thing. Nothing is different at all. The only thing I can think of is maybe she's developing a fear of the dark? Is it too early? Is anyone going through a similar thing? Help!