Areas appear to be lighted with no light sources present

In every world I generate, the world always appears to be lit up but with no light sources present. At night, the sky is dark and black but the world surface is lit up. Entering an unlit cave system makes it seem as if it has full light levels of 15 but the F3 panel says that the light level is 0. I've attached images to help with the understanding. This issue mainly causes a problem when an area is unlit and mobs spawn without me noticing.