Glycine is a non-essential amino acid (meaning that it can be made in the body and is not required from the diet) which acts as a neurotransmitter. Although glycine supplements are sometimes promoted as having a calming effect or improving sleep, the studies supporting these claims have been small, short-term, and involved a company which sells glycine. For more details, see the full answer >>
For more information, see the Encyclopedia article about Glycine.
For information about other supplements which may help to improve sleep, see the CL Answers to the questions below.