Tryptophan is an essential Amino Acid. Tryptophan is a naturally occurring amino acid that is found in many foods, most significantly in milk and bananas. This amino acid is essential to the human body for the production of serotonin, a brain chemical necessary for sleep and for mood regulation.

Tryptophan is also the nutrient that the body uses to make melatonin. It is a precursor for serotonin (which aids sleep and anxiety),and helps in niacin (B vitamins) production. Foods that are considered sources of tryptophan are dairy products, beef, poultry, barley, brown rice, fish, soybeans, and peanuts. Tryptophan is a component of many plant and animal proteins, and a normal part of the diet that humans must get from outside sources. It also happens to be the precursor (starting material) from which our brains make serotonin, which calms you down and makes you sleepy.

L-tryptophan is a natural sedative. It is normally found in turkey meat, and many people believe it to be the cause of a sleepiness common after a Thanksgiving feast. Like other amino acids, L-Tryptophan is one of the building blocks of protein, but unlike some amino acids, L-Tryptophan is considered essential because the body cannot manufacture its own. L-Tryptophan plays many roles in animals and humans alike, but perhaps most importantly, it is an essential precursor to a number of neurotransmitters in the brain. As such, L-Tryptophan is the only substance normally found in the diet that can be converted into serotonin. Since serotonin, in turn, is converted in the brain into melatonin, L-Tryptophan clearly plays a role in balancing mood and sleep patterns.

The conversion of L-Tryptophan to serotonin is a two-step process. First, L-Tryptophan is converted into 5-HTP (5-hydroxytryptophan) and 5-HTP is then, in turn, converted into serotonin (also known as 5-HT), one of the neurotransmitter chemicals that carries messages between brain nerve cells. Neurotransmitters are secreted by one cell and picked up by receptor proteins on the surface of another cell. Once the message has been delivered, a neurotransmitter is either destroyed or absorbed into the cell that made it. This process is known as re-uptake. When re-uptake is inhibited, the effect of the neurotransmitter (in this case serotonin) is amplified. Neurotransmitters like serotonin are involved in the regulation of pain, pleasure, anxiety, panic, arousal, and sleep behavior (the sleep-wake cycle).