In 1977, a Norwegian team of researchers led by D. Daarskog demonstrated abnormal growth hormone responses to clinical doses of Dexedrine and Ritalin:
The findings indicate an acute and probable long-term effect of dextroamhetamine and methylphenidate on the homeostasis of growth hormone. The possible long-term effects of these drugs on the growth of children indicates the need for caution in the widespread use of these agents.
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In 1990, Deborah Jacobovitz with a research team wrote:
Research reveals that methylphenidate stimulates daytime release of growth hormone, disrupting the usual nocturnal release. this is troublesome since disturbances n the normal release of growth hormone may not only influence height \velocity but may also impact on other critical aspects of physical development such as sexual maturation.
(Jacobovitz, D., Sroufe, L.A., Stewart, M., and Leffert.N. (1990) Treatment of Attentional and hyperactivity Problems in Children, Journal of American Academy of Child and Adolescent Psychiatry.)