Riordan & Auerbach's "Breastfeeding & Human Lactation," p. 110, cites
several studies showing that "in addition to yielding milk and calories,
suckling facilitates feelings of calm, reduces heart rate and metabolic
rate and elevates pain thresholds."

Also, look in the Lactnet archives for posts on how the vagal
stimulation of sucking and the presence of food prompts baby's own GI
tract to produce CCK, a hormone that promotes sleepiness.

One question would be whether all sucking is equal -- whether the
physiological reaction is the same, whether the baby is doing normal
suckling with the full activity with jaw and tongue, or more passive
sucking on an artificial nipple.

But an artificial nipple might be better than nothing -- as has been
suggested, the research done with preemies could be relevant.  Cup
feeding might make sense as an alternative feeding method for a short
period en-route to breastfeeding.  But as the sole, long-term feeding
method, it seems stressful.

Margaret Wills, LLLL, IBCLC

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