Although experts have expressed concerns about how melatonin could affect puberty, limited research thus far has not shown any effect. Late puberty is a condition where children do not show signs of puberty like growth of body hair, breast development, and voice deepening by the ages of 13 to 14. Puberty is driven by changes in hormones, and melatonin itself is a hormone. Experts have raised concerns that extended use of melatonin could disrupt the normal interaction of hormones, including the decline in melatonin levels, that occurs when puberty begins. Long-term research studies are needed to determine whether kids who use melatonin experience changes in development.