Pineal

A pea sized endocrine gland, found between the two hemispheres of the brain.

Melatonin

Produces melatonin, which is only vaguely understood, but does stuff in the realms of sleep cycles, antioxidants and immune system. No one has any real idea what though.

Clinical conditions

Err… some type of cancer?

Unless they say “very high levels of melatonin”, don’t even think about it.