That’s an excellent question. Evolutionary biology isn’t my field, but a guess would be giving the brain time to work on problems or sort out issues that the sensory clutter of the waking world doesn’t provide sufficient time for. I know my cat dreams, and when I had dogs, they did too. So it clearly must serve some purpose in higher order animals.

I would guess that there are numerous genes involved in dreaming, but there, we really do need someone well steeped in brain function and chemistry to chime in.

I think it is down time for restoration and repair of the whole system. I think repairs occur on the cellular level. The brain needs time free from processing sensory input.

I think sleep evolved right along with more complex creatures and dreaming with it.

I figure it is your brain working on problems and scenarios that might happen in the future.
It is a chance to work out and practice without expending energy.

If Adriana Lima ever rings my doorbell I will know just what to do.

I believe that in some of the the theories behind dreaming, dreams are a side-effect of the brain writing the short-term memories into it’s long-term memory databank. So really, the evolutionary fitness would come from being able to remember that saber-tooth tigers bite while the other guy doesn’t remember it and has to learn that lesson every day, with the dreams simply being a side effect.

It may simply be that the trait did not cause any significant disadvantage and was thus not bred out.

However, I’m not well educated enough in neuroscience to comment on the specifics.

@Seek_Kolinahr I think has it. The chemical is widely present in plant life. It is not survival of the fittest, it is survival of the adequate. Non-harmful genetic qualities hang around forever.

It is an excellent question. I haven’t a clue.

My son just graduated with a degree in Neurophysics and he doesn’t have a clue either.

To keep you asleep while your body rests.

Not sure I can buy that @talljasperman. That would seem an evolutionary disadvantage to me. The wilderness is friend to very light sleepers.

@RealEyesRealizeRealLies Picking up on that, could it be a way of assuring the brain retains a sufficient level if real-world awareness even when you are asleep?

I really can’t argue against any suggestion here. I’m actually wondering what evolutionary advantage there is to sleep in general. Wouldn’t we be more productive and alert to predation?

Perhaps it would require too much energy and greater food resources. Evolution advantages the ones who consume the least?

@RealEyesRealizeRealLies Sleep is regenerative. Sleep deprivation results in confusion of thought, slowing or reaction times and eventually psychosis, worsening health and early death.

Sure I get that. But still wonder why we don’t sleep like giraffes, less than two hours a day. But I guess they’re always eating to put energy into that massive heart pumping blood up the neck. Not much time they have for making war plans or building telescopes and space shuttles.

Dogs dream. I think it is a result of having a certain amount of intelligence, like a side effect. It wasn’t an advantage, but it posed no harm to us, either. My theory is that when a brain has a certain amount of intelligence and carries and processes so many memories and lessons, it needs to ‘defrag’ like a computer hard drive. Placing memories and lessons together in relationship to each other in our brains for easier retrieval later and also for the retention of these experiences.
I believe the theory about sleep time has something to do with safety from predators. It becomes a positive feedback loop. The safer a species becomes from harm during sleep, the better the brain and nervous system can develop and the more complex the brain and cognitive functions, the more sleep we require and the more clever we were to avoid harm from predators. Just and idea from things I’ve read and watched.

Ooooo! Here’s a possibility.
We know brain cells quickly die when deprived of oxygen. We also know from brain scans and sleep studies that dreaming stimulates various portions of the brain. So…

Is it possible dreaming periodically keeps blood flowing and oxygenates areas of the brain that are shut down or are at rest? Males have nocturnal erections to keep blood flowing to the penis. In another thread we spoke about wet dreams. Maybe the two serve a similar purpose – to reduce the chances of atrophy.
I’ll ask Adriana the next time I see her – in my dreams.