An essential amino acid in the L-Tryptophan supplement increases brain levels of serotonin, a calming neurotransmitter, and melatonin, which helps induce sleep. The amino acid L-Tryptophan may be perfectly suited to help with moodiness and sleep patterns because it promotes a bright mood, relaxed mindset, and restful sleep patterns, all at the same time. L-Tryptophan has been suggested to be important in sleep management because, unlike some synthetic sleep aids, it is not associated with feelings of grogginess and brain fog upon waking. It’s an amino acid the body does not produce, so the only way to get it is through diet and/or supplementation.