The Stanford researchers believe fibromyalgia is a neuro-inflammatory disorder characterized by 'hyper-sensitive' microglial cells; the main immune cells in the central nervous system.
Structurally similar to the macrophages found in the body, resting microglial cells display little activity but transform themselves, after being activated by inflammation, infection or cell death, into 'hairy monsters' that spew out pro-inflammatory cytokines, excitatory amino acids such as glutamate and nitric oxide with glutamate being a primary agent of damage. (Interestingly, glutamate production appears to be associated with reduced glutathione levels that occur during microglial activation. )
Microglial cells are responsible for producing neuropathic pain and flu-like symptoms such as pain, fatigue, etc. (eg sickness behavior). Rodent studies suggest LDN blocks the activity of toll-like receptors (TLR4) found on the microglial cells.
It is usually best to start with 1.5 mg and every week or two increase. Go to 3 then 4.5 then 6mg. Most people find 1.5 isn't enough and 6 is too much and 3 or 4.5 is the best. Finding what is not enough and what is too much helps pinpoint the right dose. Every few months decrease and increase again to check that your requirement hasn't changed.