Sometimes when you have a lucid dream or you astral travel, places can bee very much dark, like if it were night and its hard to see.
In order to increase the ammount of light in a dream, pray to your divine mother with devotion and ask her to increase the light, you will see suddenly an increase of light.
… or you can just order your dream to have more light … 
In my last lucid dream I was having problems with that, I’m not sure what you mean by divine mother but I think I will try asking my DG to help me out a little bit 
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You can also use a light switch. If you expect the dream to become more light, it will.
Well, yes, praying to a divine entity could work if you believe in the power of that entity, but that’s mostly like any other dream command. I don’t believe in a divine mother, so I doubt she’d be much help to me 