Beta is impossibly dark at night and in caves

Now I know caves and nighttime are supposed to be dark.  But it is so dark in caves and at night that I can't play at all.  This is a real issue when phone screens are already pretty tiny.  I have to stop and wait for daylight, which is tedious and battery-consuming.  And that's only if the monsters I can't see don't rip me apart.  Adjusting the brightness doesn't help.  I just bought this game for my phone so I could join the beta.  The current situation doesn't make me want to keep playing.