If we are to make infants' lives as pleasant as possible, it is important to know their needs. For anyone caring for a small child, this can often be a guessing game. That is why it is important to differentiate between those needs, so that we can satisfy them. Above all, we should differentiate clearly between nutritive and non-nutritive sucking, because they serve completely different purposes and therefore meet two different needs.
Non-nutritive sucking or NNS has a soothing effect on infants and toddlers. Being able to calm oneself means taking responsibility for one's own wellbeing, so non-nutritive sucking can therefore be described as a resource in the psychological sense. It is a question of having the ability or skill to minimise distressing influences from within, as well as externally. It is particularly relevant that thumb-sucking happens even during the embryonic stage of development, when the baby is being fed through the umbilical cord. We can therefore assume that thumb-sucking during this phase is not connected with the intake of nutrients and obviously must fulfil some other purpose.
It is also observed in animals that mammals such as monkeys also suck their thumbs.
If we analyse sucking more closely, we see that it exerts pressure on the tongue and the roof of the mouth. That pressure becomes stronger, the more resistance there is between the tongue and the roof of the mouth, for example due to a thumb or a soother. Sucking also creates a rhythmic movement. This results in neuro-stimulation of the tongue, because there are about 50,000 nerve endings on the tongue, which is directly connected to the central nervous system (Doiges, 2015). Particular points on the tongue and the roof of the mouth are stimulated by sucking and the meridians are activated in a similar way to acupressure, leading to self-regulation.
This is why, in the millennia-old practice of TCM - Traditional Chinese Medicine - the tongue is examined and diagnosed, because the meridians or energy pathways and indeed the nerve paths connect the tongue and the organs together. According to TCM, the whole person is reflected on the tongue, as it is also in the palm of the hand, on the soles of the feet and in the ear. The tongue is divided into areas (see diagram) and mirrors what is going on everywhere in the body, so the condition of important organs can be detected from the tongue. The spleen and kidney meridians also end at the root of the tongue (Kaptchuk, 2006, p. 105, p. 112).
For over a thousand years, various types of movement therapy have become more and more widespread, be that Qigong, Taekwondo, Shiatsu, Tai Chi, DO-IN, acupuncture, acupressure, breathing therapy or yoga. Nowadays, they are becoming increasingly popular in western society because of the beneficial effects they have on body and mind. In all the Far Eastern movement techniques mentioned above, the tongue is placed on the roof of the mouth. This closes the energy cycle and stimulates the flow of Qi through the meridians. Putting the tongue in this position has a similar effect to sucking on a soother.
The "tongue on the roof of the mouth" exercise can have a generally calming and relaxing effect as well as increasing concentration and performance. Apart from improving physical health, for example of the respiratory tract, it also reduces the sensation of pain. In very simple terms, pressure on the soft palate and the tip of the tongue stimulates the vagus nerve which triggers a relaxation reflex, bringing the body and mind to rest so that regeneration can begin. This gives rise to the hypothesis that putting the tongue in this position may have a kind of switching function, stimulating self-regulation and regeneration, restoring balance and reorganising the body. There is a clear similarity with the sucking action. From this we can deduce the effect of sucking, because the stimulation of the tongue and the roof of the mouth during sucking activates the same areas of the brain, due to the connection with the vagus nerve. It therefore makes complete sense that this should be a psychological resource dating from pre-natal development and infancy, one which all Eastern movement techniques have known how to make use of for thousands of years.
DOIDGE Doiges (2015): Wie das Gehirn Heilt. Neueste Erkenntnisse aus der Neurowissenschaft. (How the brain heals. The latest findings from neuroscience.) Frankfurt/New York: Campus Verlag. (p. 215, 286 and 291).
KAPTCHUK Ted J. (2008): Das große Buch der Chinesischen Medizin. (The big book of Chinese Medicine) Frankfurt am Main: Fischer Verlag.
MACIKOCCIA Giovanni (1994): The Foundations of Chinese Medicine. A Comprehensive Text for Acupuncturists and Herbalists. Kötzting/Bayer: Publisher for TCM, Dr. Erich Wühr, Wald.
MICHIO Kushi (1994): DO-IN. Exercise for Physical and Spiritual Development. Münster: Verlag Mahajiva, (the original version was published in Japan in 1979).
TRÖKES, Anna, STEINER Ronald (2012): Yoga für Fortgeschrittene. (Advanced Yoga). Munich: Gräfe und Unszer Verlag.
VOTSMEIER-Röhr, A. (2004): Selbstregulierung in der Gestalttherapie. (Self-regulation in gestalt therapy). Geisler, P. (Pub.): Gießen: Psychosozial-Verlag
VOTSMEIER-Röhr, A. (2011): Gestalttherapie und Neurowissenschaft. (Gestalt Therapy and Neuroscience). Göttingen: Reinhardt Ernst.