Vitamin B1, also known as thiamine, has a well-established role in nervous system function. Thiamine acts as a coenzyme in carbohydrate metabolism, which is essential for energy production in neural tissues. Deficiency of thiamine can lead to neurological syndromes such as beriberi and Wernicke-Korsakoff syndrome, both characterized by symptoms of nervous exhaustion, fatigue, irritability, and cognitive disturbances.

The use of vitamin B1 to treat "nervous exhaustion"—a historical term often used to describe symptoms related to fatigue, weakness, and mental burnout—has a scientific basis, particularly in cases where thiamine deficiency is present. Clinical studies and case reports document the reversal of neurological and psychological symptoms following thiamine supplementation in deficient individuals. However, for individuals without a deficiency, evidence supporting the use of thiamine specifically to treat nonspecific "nervous exhaustion" is limited. Most clinical benefit is observed when exhaustion is linked to a measurable deficiency or alcohol abuse.

Therefore, while there is scientific validation for vitamin B1’s critical role in nervous system health and its ability to reverse symptoms of deficiency, there is less robust evidence supporting its use beyond this context. Supplementation in the absence of deficiency shows limited benefit for general nervous exhaustion, and more research is needed in this area.