A few newb questions about this wonderful game

What an amazing experience so far. So many great things about this game. But I’m confused by the following:

• what is the consequence of increasing panic? You don’t sleep, you enter a panicked state more easily. But then what? Does the amount of “bad stuff” happening then increase e.g. a huge fish attacking you?

• what does it mean when certain islands appear “darkened” in the map? I’m still in The Marrows but I visited a small island right off its coast, and circled it, and it’s still lightly shaded.

• at night, does the green swirly thing over a fishing spot mean you’ll definitely get an aberration? Or trophy?

• is there a lower chance for aberrations during the daytime?

Thank you to anyone who can help me out!