I was just reading how brain entrainment can effect hormone levels in your body: http://www.project-meditation.org/c...cial-hormones-released-during-meditation.html I appreciate that if these certain hormones are released or reduced it has beneficial effects in normal circumstances (nothing to do with entrainment), such as your body naturally releasing more serotonin. Entrainment then induces this process and increases the good hormones, and decreases the bad hormones, thus making you feel better on many levels. However, how do we know the effect of doing this is safe. What solid scientific research is there on this. From what I've seen its still relatively conflicting, and since audio driven brain entrainment is relatively new we don't know its long term effects. For example. Cortisol has an important function in the immune system: The Purpose of Cortisol and Corticosterone Summed up: When you compare that to Project Meditation's description of Cortisol it is very different (and the skeptic may say biased): More of cortisol does cause stress and weaken the immune system, but it is there for a reason, to regulate your immune system. So how does messing with the bodies natural defense make you healthier? It seems comparable to drugs which increase certain hormones (or mimic them) but longer term have negative effects? Does anybody know of scientific studies for or against entrainment's effect on hormone levels?