How is melatonin made?

Melatonin is a hormone that is produced primarily in the pineal gland of the brain. Its synthesis involves several biochemical steps from the amino acid tryptophan. Here’s a simplified overview of how melatonin is made: 1. **Tryptophan Hydroxylation**: The process begins with the amino acid tryptophan, which is converted into 5-hydroxytryptophan (5-HTP) through the action of the enzyme tryptophan hydroxylase. This enzyme adds a hydroxyl group to tryptophan. 2. **Decarboxylation**: Next, 5-HTP undergoes decarboxylation, where a carboxyl group is removed, resulting in the formation of serotonin (5-hydroxytryptamine, or 5-HT). 3. **Acetylation**: Serotonin is then converted into N-acetylserotonin through the action of the enzyme arylalkylamine N-acetyltransferase (AANAT), which adds an acetyl group. 4. **Methylation**: Finally, N-acetylserotonin is converted into melatonin by the enzyme hydroxyindole O-methyltransferase (HIOMT), which adds a methyl group to the molecule. This entire process is regulated by several factors, including light exposure. Melatonin production is generally stimulated in darkness and inhibited by light, which is why it is often referred to as the "sleep hormone." Melatonin is not only produced in the pineal gland but also in smaller amounts in other tissues, such as the gastrointestinal tract and the retina.