This question tests the understanding of Cartwright's advice on when to pay attention to dreams. The text clearly states that there's little reason to pay attention to dreams unless they keep us from sleeping or we wake up in a panic. This makes option C the correct answer. Option A is incorrect because the text does not advocate for always paying attention to dreams. Option B is not supported by the text, which does not mention the pleasantness of dreams as a criterion. Option D is incorrect because the text does not deem all dreams as meaningless.