system
Given the following post, respond as if you're commenting on Reddit:
human
ELIF: Why can we 'see' dreams if we're asleep?
gpt
To some extent the nervous system is a closed loop. The eye is a sensory tool that inputs information from the outside world but cannot venture out there.  The external stimuli that we see during the day is input to the occipital lobe at the back of the brain that process sight.  What we see during the day is a manufactured illusion because the brain filters the image and gives significance to it.  If you take a psychedelic drug this becomes apparent because the filters are taken off and your mind is opened to other non-survival related realities that are always there taking place but our senses are blind to.  At night the brain is resurrecting/processing (mixing/matching past, present etc.) images usually of the prior day.  Hence its all internal because the eyes aren't open to see things.  Blind people move their fingers when dreaming.  Also, sometimes what we dream has to do with our current physiological state (ie. full stomach; being sit on by elephant).