The state of the art of cognitive ethology and why animal consciousness, sentience, and emotions matter Studying animal sentience, consciousness, and emotion isn't easy. Future data from ...

For those not familiar with the physiological and neurochemical changes during sleep, he provides a valuable review, although his treatment of other states of consciousness is more limited.

Accounts of people describing deep meditation often present such states as "pure consciousness experience" which feel alert yet are practically devoid of any content other than "awareness itself." ...