I agree with Jan B.,  non-nutritive sucking has a physiologic as well as
psychologic effect.   My colleagues in the neonatal intensive care unit are
big believers in NNS, particularly in premies. NNS is known to stimulate
the production of lingual lipase, and other gastric hormones which assist
in digestion of milk, and a more rapid development of the GI tract. Place a
pacifier in your mouth and see what happens, the mouth produces enzymes and
fluid that is subsequently swollowed,  hence assisting digestion of
ingested food.  It actually works great( in between breastfeeding).


Tom Hale