of a situation, easier to be objective in emotionally or morally difficult situations, and easier to achieve a state of responsive, creative awareness or "flow". Research from Harvard medical school also shows that during meditation, physiological signals show that there is a decrease in respiration and increase in heart rate and blood oxygen saturation levels.Meditation and stressNational Institutes of HealthAccording to the National Institutes of Health (NIH), "Practicing meditation has been shown to induce some changes in the body...Some types of meditation might work by affecting the autonomic (involuntary) nervous system." The sympathetic nervous system and parasympathetic nervous system are two divisions of the autonomic nervous system of the body. The sympathetic nervous system is responsible for our reaction to stress or fear and is colloquially known as the "fight-or-flight" system. The parasympathetic nervous system is active during times of rest and associated with "rest and digest". The NIH goes on, "It is thought that some types of meditation might work by reducing activity in the sympathetic nervous system and increasing activity in the parasympathetic nervous system."Goleman: Amygdala and pre-frontal cortexOne theory, presented by Daniel Goleman & Tara Bennett-Goleman[19] suggests that meditation[clarification needed] works because of the relationship between the amygdala and the prefrontal cortex.[20] In very simple terms, the amygdala is the part of the brain that decides if we should get angry or anxious (among other things), and the pre-frontal cortex is the part that makes us stop and think about things (it is also known as the inhibitory centre).The prefrontal cortex is very good at analyzing and planning, but it takes a long time to make decisions. The amygdala, on the other hand, is simpler (and older [21] in evolutionary terms). It makes rapid judgments about a situation and has a powerful effect on our emotions and behaviour, linked to survival needs. For example, if a human sees a lion leaping out at them, the amygdala will trigger a fight or flight response long before the prefrontal cortex responds.But in making snap judgments, our amygdalas are prone to error[citation needed], such as seeing danger where there is none.[citation needed] This is particularly true in contemporary society where social conflicts are far more common than encounters with predators, and a basically harmless but emotionally charged situation can trigger uncontrollable fear or anger leading to conflict, anxiety, and stress.[22]Gray and White MatterStudies done by Yale, Harvard, Massachusetts General Hospital have shown that meditation increases gray matter in the brain and slows down the deterioration of the brain as a part of the natural aging process.The experiment included 20 individuals with intensive Buddhist "insight meditation" training and 15 who did not meditate. The brain scan revealed that those who meditated have an increased thickness of gray matter in parts of the brain that are responsible for attention and processing sensory input. The increase in thickness ranged between .004 and .008 inches (3.175 x 106m - 6.35 x 10 6m) and was proportional to the amount of meditation. The study also showed that meditation helps slow down brain deterioration due to aging.A study