Tony,
Thanks for the post... Good questions too. One of the short answers is 25(OH)D is the best measure of vitamin D3 status. 1,25(OH)2)3, a.k.a. calcitriol can be measured... but it is not a reliable biomarker. The other is 60 to 80 ng/mL is the optimum range for the 25(OH)D serum concentration for sleep according to Dr. Stasha Gominak, MD.
She's a neurologist in Tyler, TX who suggests a vitamin D3 regimen very similar to the anti-inflammatory regimen for her patients suffering from sleep, chronic pain and headache disorders.
The only real difference is she also suggests a 3-month course of vitamin B 50. Taking vitamin B 50 for more than 3 months starts cutting into the good sleep benefits. She has some excellent videos on her regimen at the following link: Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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Understanding a little about vitamin D3 pharmacokinetics, what the body does to vitamin D3, might help in understanding the above answers.
No matter how we get vitamin D3, from the UV-B in sunlight generating vitamin D3 in the skin or from supplemental intake, the first thing that happens is vitamin D3 is metabolized by the liver into 25-Hydroxyvitamin D3. This is an unregulated process that continues until the liver has metabolized the available vitamin D3 to 25-Hydroxyvitamin D3.
Chemically what happens here is an enzyme in the liver adds a hydroxyl radical, [OH], to the 25th carbon position on the vitamin D3 molecule, hence the name 25-Hydroxyvitamin D3 or 25(OH)D, also called calcidiol.
This is a stable metabolite of vitamin D3 with a half-life of 2 to 3 weeks depending on the serum concentration. Roughly 20% of the serum 25(OH)D is further metabolized in the kidneys by another enzyme, 1α-hydroxylase that adds a second hydroxyl radical to the 1st carbon position on the vitamin D3 molecule, hence the chemical name 1,25(OH)2D3.
1,25(OH)2D3 is the active hormonal form of vitamin D3 also called calcitriol. The normal serum concentration of calcitriol is one thousand times less than the serum concentration of calcidiol, a.k.a., 25(OH)D. It has a serum concentration half-life of roughly 7 hours...
This path of vitamin D3 metabolism helps maintain serum calcium concentrations, through one of the body's control mechanisms called calcium homeostasis. Calcium homeostasis is controlled by the parathyroid glands that secrete parathyroid hormone (PTH).
When the serum calcium concentration is near the low end of its normal reference range, the parathyroids sense this condition and release more PTH. This signals the kidneys to produce more 1,25(OH)2D3 that pulls dietary and supplemental calcium from the gut to keep serum calcium in an optimum concentration. This process also helps build bone mineral density... i.e., strong bones. When the serum calcium concentration is near the upper end of its normal reference range, the parathyroids sense this condition an slow the production of PTH.
The other 80% of the serum 25(OH)D produced by the liver gets hydroxylated to 1,25(OH)2D3, extrarenal, (outside the kidneys) in cells throughout the body by the same 1α-hydroxylase enzyme. These molecules of vitamin D3 link up with a molecule of vitamin A (retinol) and physically attache to genes as specific sites called vitamin D receptors, (VDR).
It's this path of vitamin D3 metabolism that's responsible for what is called genetic expression, a process that basically enables the cells to unlock their genetic libraries of instructions to do a number of things, like multiply, differentiate, control the production of special products, or die.
I realize at this point, some of you are convinced I've had a senior moment, gone off the deep end or lost the bubble completely. Stick with me a bit longer and you'll see where I'm going with all this...
It turns out that nerve cells in the human brain produce the 1α-hydroxylase enzyme and that VDR have been found in nerve cells throughout the brain. What is particularly curious about all this is... the highest concentrations of VDR and the 1α-hydroxylase enzyme in the brain are found in the hypothalimus and trigeminal ganglia nerve cells.
For CH'ers new to this disorder, the big dog neurologists and experts on cluster headache all opine the hypothalamus is the head waters for the pathogenesis of cluster headache. In other words, they think the hypothalamus manages the processes that control cluster headache. They'll also tell you the trigeminal ganglia are where all the cluster headache pain we suffer originates...
If you've studied human physiology and anatomy, you're also likely familiar with the fact that the hypothalamus is part of the autonomic nervous system that controls sleep and the body's other circadian rhythms.
If you're like a lot of us, at this point you've just connected the dots and experienced an "Ah Ha..." moment of insight...
Sleep and cluster headache are controlled by the hypothalamus...
The hypothalamus and trigeminal ganglia are loaded with vitamin D3 receptors and the enzyme needed to convert vitamin D3 to it's active hormonal form.
And... vitamin D3 helps control the genetic expression of these nerve cells enabling them to do what they're supposed to do... like help us sleep better and not have headaches...
Now for the conclusion of this little tale... In order to make a really good soup, you need the right ingredients in the right proportions...
Magnesium, zinc and boron are needed because they support nearly all the body's enzymatic processes. Magnesium is also part of the vitamin D binding protein that transports vitamin D3 and its metabolites through the blood stream. Molecular biologists and genetics experts have found a "zinc finger" in each VDR that helps attract and attach vitamin D3 to a gene.
Omega-3 fatty acids act as potent anti-inflammatory agents and vitamin K2 helps direct the flow of serum calcium away from soft tissues and arteries towards building bone mineral density.
So here are the soup ingredients... a.k.a., the anti-inflammatory regimen supplements...
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Hope this helps...
Take care,
V/R, Batch