The Science of Consciousness:
Chapter 11: Altered States of Consciousness
What are Altered States of Consciousness (ASC), and what do they tell us about "normal" consciousness?
Links to pages on Altered States of Consciousness
Susan Blackmore's web pages. Although author of a competiting text, I recommend her pages for discussion of many fascinating topics in consciousness research, particularly parapsychology, dreams, and altered states.
Kingsland, J. (2019). Am I dreaming? The new science of consciousness and how altered states reboot the brain. London: Atlantic Books. Kindle version available. ISBN: 978-1786495501.
If you've seen the Ken Russell 1980 film Altered States, you might be under the impression that altered states are bad things. Not at all; meditation can help us relax and deal with stress, and hypnosis can help treat us for many physical and mental problems. Probably of most interest though is the work on hallucinogenic drugs, which have recently been shown to help with creativity, mental illness, finding meaning and purpose in life, and even helping us cope with fear of death, even in extremely small doses ("microdoses"). Kingsland's excellent and wide-reaching review covers all this material and more. It is approachable and clearly written, which is important given that he also covers the neuroscience of how things work. Much of the research with drugs was carried out by Robin Carhart-Harris and David Nutt, under special licence and medical supervision.