Tryptamine (3-(2-aminoethyl)indole) is a monoamine compound that is widespread in nature. Biosynthesis generally proceeds from the amino acid tryptophan, with tryptamine in turn acting as a precursor for other compounds including indole, beta-carboline and ergoline alkaloids and auxins. Substitutions to the tryptamine molecule give rise to a group of compounds collectively known as tryptamines. The most well-known tryptamines are serotonin, an important neurotransmitter, and melatonin, a hormone involved in regulating the sleep-wake cycle.