I just found this from another thread:
The thread can be found here:
http://forums.astraldynamics.com/viewtopic.php?t=1111&highlight=animals
Only part of it is relevant to this discussion (around half way down page 1)
Quote
There was an interesting programme about sleep on our local TV not so long ago. One of the points is that sleep state activities take place in the old brain and during dreaming the higher brain is switched off so analytical comprehension is not as when awake. It maybe that Lucid dreaming is the state where the higher brain is also active so the dream can be analysed with detail and so on.
It also said when in REM (rapid eye movement) sleep the measureable electrical activity is identical to being awake.
The thread can be found here:
http://forums.astraldynamics.com/viewtopic.php?t=1111&highlight=animals
Only part of it is relevant to this discussion (around half way down page 1)