Melatonin is a hormone produced by your pineal gland which controls your wake and sleep cycles. In the presence of light your retinas send signals to the brain that slow the production of melatonin so you can remain awake through the day. In the absence of light your brain produces more melatonin, which is why meditating can induce waking dreams and open your pineal gland. And here is a substance that does that for you!
Melatonin is an important hormone for anti-aging, which is why they call it "beauty sleep". When your pineal gland releases melatonin, it is absorbed into the skin and tells the skin to release anti-oxidants which heal and regenerate new, young and fresh skin cells. Melatonin also tells your skin to create chemicals that are UV-protectant, so avoid the damage to your skin.
What calcifies your pineal gland? Well, fluoride is a HUGE culprit. The fluoride in your water, the chemicals in your food and even the fluoride in your toothpaste can all build up over time to calcify your pineal gland.