In contrast, lower than normal levels are referred to as a serotonin deficiency. A deficiency causes several physical symptoms, including insomnia, carbohydrate cravings, fatigue, nausea ...

Vision problems can also be a sign of Vitamin B12 deficiency. The vitamin is vital for maintaining healthy optic nerves.

Foods rich in tryptophan may boost the production of serotonin in the brain. These foods include eggs, some cheeses, and turkey. Serotonin is a natural neurotransmitter (brain messenger ...