I am currently in remission from a lifetime of narcolepsy after adopting a gluten-free diet. I have written a paper I believe explains the pathology.

Narcolepsy, Parkinson's Disease, and Lewy Body Dementia: An Autoimmune Hypothesis

Here's a summary:
The DQB1*0602 gene which is strongly linked to narcolepsy and PD is also linked to gluten sensitivity, an autoimmune reaction to wheat and other grains. Gluten intolerance usually causes intestinal damage and gastrological symptoms, but this version is often intestinally asymptomatic. A new study shows that the gluten antibodies (antigliadin) can bind directly to tissues in the brain. There they attach to a protein inside the neurons called Synapsin I. The function of Synapsin I is to hold the neurotransmitter inside the cell until it is stimulated. I believe that when the antigliadin is attached to the Synapsin, it cannot release the neurotransmitter. Not only does this cause a loss of neurological function, it is responsible for a buildup of another protein, alpha-synuclein, forming Lewy bodies and causing cell death.

Basically, I believe gluten antibodies are clogging up your brain. And you do not need to have any other celiac symptoms for this to happen.

There are more complicated interactions between antigen genes, so having the DQB1 gene is not required, and many variations of the symptoms are possible.

Dabbo, that includes narcolepsy without cataplexy, and IH. Maybe this is the "big picture" you are looking for.