||The English used in this article may not be easy for everybody to understand. (June 2012)|
The suprachiasmatic nucleus (pronounced: supra-kye-as-matic noo-kle-us), or the plural of nucleus, nuclei, (SCN), is a small organ in the hypothalamus in middle of the brain. It is formed of two halves. It has different cell types, many peptides (including vasopressin and vasoactive intestinal peptide) and neurotransmitters.
The SCN controls our daily "body clock", including when we get sleepy and wake up, when we are active and when we get hungry. The SCN gets information about light and dark from the retina in the eye so it can adjust itself to the true 24 hours.