The virus attacks the body's immune system. Cambridge University Press; Puberty can be a difficult time for children. It is important to know that telling others — even people who are close to you — may not always be easy or pleasant. Rising leptin levels may signal the onset of puberty. All the growing and other changes going on in the body take up huge amounts of energy, so more rest is needed.
Sadly, some react with anger, hostility, or rejection.
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Ontogeny, neuroendocrinology, physiology, and disorders.