It is not yet clear whether the expression of experience-dependent neural plasticity is altered in hypocretin neurons in animals under different energy states (such as calorie restriction and obesity), through which acute and chronic changes in energy balance may shape homeostatic and cognitive functions through the hypocretin system in animals and lead to various mental or psychiatric diseases in humans. This evidence concerns the gene HCRT and obesity due to melanocortin 4 receptor deficiency.