When we close our eyes, the mind imagines a lot.
The eyes give one kind of information to the mind.
We have 6 sense doors, right? When we use all our 6 sense doors, the mind can collect 6 kinds of information, and then, the mind can think the right way.
If the mind receives any less information, that’s not enough for the mind to think the right way.
When we close our eyes, it goes into a world of imagination (daydreams) and thinking.