The critical element here, to me, is the cockeyed angle of the window, suggesting that the light tumbles in, as if drawn by gravity. The window, I imagine, is in a slanting roof, but it seems disengaged from the rest of the scene, floating in the black space, perhaps tumbling itself, in which case the light will fall on the woman and then it will leave her in the darkness after a moment. For now, though, she enjoys basking in it. A beautiful, haunting, but also cheerful picture. Felicitations!