Browsing the web yesterday, I found an old blog post in which the author mentions that melatonin is made not only in the pineal gland, but also in the gastrointestinal tract (in the enterochromaffin cells) and oddly, the retina of the eye. Since this is an old post, I am trying to track down his facts and see if there is any corroborating evidence in the scientific literature. I did find a few papers that treat of this topic. One abstract is here and another full paper is here.
He also indicates that there is way more melatonin in the gastro tract than the pineal gland secretes normally (only 3 micrograms). And further that taking melatonin orally does not interfere with the pineal gland's production. This would be good news indeed, if true.
I have also been coming across descriptions of SAD symptoms and the various remedies people try to overcome that problem. SAD is the acronym for seasonal affective disorder. This is the winter blues that was much more prevalent back in New England where I came from than it is here in sunny So. California. My mother thought she suffered from this. One of the treatments is to sit in front of a bright light, or just to get outdoors more in the winter. Many of the people suffering from this disorder say they feel like they want to hibernate in the winter and after reading Wiley's book (Lights Out), I am wondering if the SAD sufferers aren't the normal ones and those of us who pay no attention to the change of seasons are the abnormal ones. The connection to my current research is that SAD makes one too sleepy (for modern living) and the cure is to make more serotonin (one theory) by sitting in the light. I found the bit about how shining a light pen on the back of a person's knee could shift their circadian rhythms really fascinating. That's in Wiley's book, too, and is the reason she advocates total darkness for sleep.
But there is one problem with this that I have been thinking about, and maybe you have thought of it, too. Not every night is totally black. Every month the moon goes through its cycles and when it is full, it can be bright enough to cast a shadow. Over at the Weston Price Foundation, they have come up with another hypothesis as to how this affects the human animal. (I'll give you a hint: think cycle.) Check out this page and scroll down to the paragraphs on Night Lighting. Even if you are not planning to get pregnant, you will find this interesting.
You can see how melatonin production--and thereby sleeping in darkness or with light--can affect the whole body's functioning, including the menstrual cycle: if the hypothalamus doesn't receive sufficient melatonin, its ability to regulate the hormonal system will be impaired.
Neat, huh? The story of prolactin will have to wait until the next time.