The orexin/hypocretin neurons (same nuclei, different names) are the brain’s ATP and glucose sensors. Responsible for maintaing wakefulnesss, arousal, and feeding initiation, these neurons require five to six times the amount of ATP to fire. When ATP is low due to Thiamine deficiency, firing diminishes or ceases and fatigue, sleep, and anorexia ensue. Similiarly, when glucose concentrations are elevated firing diminishes significantly (via an ATP-dependent, inward rectifying K+ channel). One of the precursors of ATP is TPP (Thiamine pyrophosphate), a Thiamine dependent Glycolysis cycle. Ablation and/or mutation of these neurons induce narcolepsy and cataplexy, as well as, environmental intervention in your caloric intake. Eg. Change in diet.
In a study conducted at the University of Tokyo, 30 patients with narcolepsy were given L-Carnitine (510 mg/day) or placebo in a randomized, double-blind, cross-over and placebo-controlled trial. Results revealed that total time for dozing off during daytime in narcolepsy patients, the primary end point, was significantly decreased by L-carnitine supplementation compared with placebo. L-Carnitine supplementation also increased serum Carnitine levels and reduced serum triglycerides concentration indicating improvement in burning of fat as energy.