The pineal body: cones, clocks and sand

The Weekend Australian - Travel - - Resources -

What is it? A small gland that sits near the cen­tre of our brain, in a groove be­tween each hemi­sphere (side). In chil­dren it’s only about 8mm long and maybe 9mm wide, and it gets even smaller as we get older. It’s part of the body’s en­docrine sys­tem, which means it pro­duces hor­mones that travel to other, tar­get, or­gans and thus reg­u­late body pro­cesses. Where does the name come from? Pineal is from Latin word pinea , which means pine cone— it’s said to be shaped like one. What’s it got to do with sleep? It makes the hor­mone mela­tonin, but rel­a­tively lit­tle is un­der­stood about the ef­fect that ei­ther this tiny gland, or mela­tonin, has on the body. Mela­tonin is se­creted par­tic­u­larly dur­ing the night rather than the day. In some an­i­mals the pineal gland is di­rectly sen­si­tive to light, but in hu­mans, cells in our eye trans­mit sig­nals to the gland, telling it when it’s light and dark.

This rhyth­mi­cal cy­cle of mela­tonin se­cre­tion is be­lieved to reg­u­late the body’s in­ter­nal clock, telling us when to sleep and when to wake up.

For th­ese rea­sons some re­searchers be­lieve tak­ing mela­tonin can help treat sleep prob­lems such as jet lag and in­som­nia, es­pe­cially in the el­derly, as we seem to pro­duce less mela­tonin as we get older. Why might you see your own pineal body? It some­times has small de­posits of cal­cium in it, and th­ese can show up on skull X-rays. Th­ese lit­tle gritty par­ti­cles are called ‘‘ brain sand’’.

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