Glycine is the most important non-essential amino acid in humans. It is very effective in improving health and well-being. Numerous clinical studies have shown that taking glycine one hour before bedtime improves sleep quality and reduces sleepiness and fatigue during the day (1). One of the possible explanations for this is that glycine activates a very specific part of the brain that leads to a decrease in body temperature, which eventually makes us fall asleep (2).