He also looks at the possibility that most of what is taken to be jhana is in fact hypnosis, and the way in which notions of "superhuman states" crept into the textual sources.My experience as a long-term meditator, as well as a person who arguably thinks too much, leads me to feel that mindfulness is really the key to Dharma practice—not so much the eradication of unskillful mental states as the neutralization of them through the detachment and non-identification of mindful awareness. The thing is, though, that we cannot detach from what we are oblivious to. Deeper jhānas, which are "purifications of mindfulness," allow the meditator to be mindful of subtle states that the ordinary person walking around and making noise does not even suspect the existence of.
The more awake and attentive one is, the more subtle the phenomena one is able to observe, thereby "transmuting" it into awareness. The four jhānas are, according to this interpretation, the progression of meditation from the most obvious, crudest phenomena, which is all most people tend to be aware of, to the most refined, until the whole field of consciousness is no longer subconscious, or semiconscious, but conscious.
Even in fourth jhāna a meditator would be conscious; in fact he or she would be more conscious than an ordinary person in an ordinary waking state. One would not be oblivious to anything; it would simply become irrelevant, and remain undiscriminated. In this sense advanced jhāna may be said to be a kind of temporary, artificial enlightenment; in the texts jhāna is called “temporary liberation” (samaya vimokkha).
http://thebahiyablog.blogspot.co.uk/201 ... or-on.html
As ever, worth reading, even if you end up disagreeing with him.