In the last few decades, a neurological understanding of the meditative process has been slowly emerging. It started with some simple observations of what happens when one progressively reaches deeper stages of meditation.
Although we remain wakeful, in progressively deeper stages of meditation, fundamental changes start happening in our body and brain. Most striking of these changes is a sharp drop in our metabolic requirements, as the whole integrated system of body and mind seems to undergo a slowdown. The brain is a major energy consuming organ in our body, and as its slowdown begins, so does the activity of systems supporting it ( respiratory movements, cardiac pumping) goes down several notches. The result is a sharp drop in basal metabolic rate, estimated to be about 13% in one recent study.(1)
– Peter MacWilliams
The second most consistent physiological finding observed in meditators has been a sharp drop in activity of the sympathetic nervous system. This system of nerves and parts of the brain are mostly active in situations of stress, fear and panic amongst others, provoking what is typically known as the ‘flight or fight reaction’. At the same time, the parasympathetic system, which in many ways acts as the opposite of the sympathetic system gets into an overdrive. This typical situation is characteristic of the states of relaxation and rest, and has been noted in several studies of meditation.(2,3)
Therefore, this hypo-metabolic parasympathetic predominant state of the mind is quite different from the states of deep sleep, dreams and wakefulness. These 3 categories have been conventionally the only 3 recognised states of the mind in western psychology; but in several Eastern and Western religious and mystical traditions, the presence of the 4th state of mindfulness or ‘thoughtless awareness’ is recognised. In this state of the mind, a peaceful and tranquil feeling of relaxation is commonly reported, a process which is analogous to deep mental silence, as the mind takes rest from non-stop thoughts. Our recent observations suggest that this indeed has features distinct enough to be called the ‘Fourth State of Mind’.
There are various forms of meditation, which aim to achieve states ranging from simple relaxation of the mind to deeper, profound states of removing ‘mental clutter’. In future articles of this series, we would be looking at the neurophysiological mechanisms of these states and their practical utility in our lives.
(1) Chaya, Kurpad et al (2006). The effect of long term combined yoga practice on the basal metabolic rate of healthy adults. BMC Complement Altern Med. 2006; 6: 28. Available online at : http://www.biomedcentral.com/1472-6882/6/28
(2) Cahn, B.R., Polich, J., 2006. Meditation states and traits: EEG, ERP, and neuroimaging
studies. Psychological Bulletin 132 (2), 180–211.
(3) Jevning, R., Wallace, R.K., Beidebach, M., 1992. The physiology of meditation – a
review – a wakeful hypometabolic integrated response. Neuroscience and
Biobehavioral Reviews 16 (3), 415–424.
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