Twenty years ago I tried to figure out what kinds of things prompted me to have interesting dreams. This means that I would make notes in my journal about ambient issues at the time I went to sleep or when I woke. Some entries describe going to bed with a headache (and waking with one), noisy neighbors keeping me up, goals for things I wanted to dream about, if I was sick, etc. Of all the many varieties of external conditions I could think of, I couldn't find strong evidence that anything influenced my dreams at all.
Occasionally I would have a dream that reflected my goal for the evening, but this was very rare and highly specific. Sometimes it seemed to work if: I tried to see a certain person in an oobe, or I prayed for an answer to a question. I did not dream of random thoughts of the day, but if I meditated enough on seeing one person and only that person, I found that I could occasionally accomplish exactly that. Then, I would go see several other people, often in different states and all on the same night. The same is true for meditating on getting the answer to a question. The common factor is meditation. I concentrated on achieving these goals and sometimes it worked. However, other goals that I meditated on never happened. I could go see someone specific or I could get an answer. I did not dream of any other specific subject on request (such as winning lottery numbers, future disasters, etc.)
For awhile I thought that fatigue affected my sleep to such an extent that I would surely have poor recall on mornings after fitful sleep, only a few hours of sleep, or deep sleep after too many hours of wakefulness. But then I had a couple of extremely profound dreams while utterly fatigued. Another theory shot to pieces.
So tonight I am going to bed utterly exhausted. I am working on a PhD, have a full-time job, and am about to pitch a big project that I've had to prepare for. My thought as I sat down to write this was that "there is no way I remember anything tonight", but then I've been proven wrong before in these circumstances. Not only that, I am almost always wrong when I try to link physical conditions with dream experiences.
This makes me wonder if it could be used as a tiny little prop to buttress a dualistic view of mind and spirit? After all, if the body's condition has no effect on dreaming at all, and dreaming is an expression of consciousness, then perhaps consciousness is not body-centric. We'll see if there is anything interesting to report tomorrow morning. Until then,