Glycine Reduces Daytime Fatigue After Poor Sleep.

In 2012, Makoto Bannai and team from Ajinomoto Co., Inc. tested 7 healthy men (average age 40.6) who slept 25% less than usual for three nights. They took 3 grams of glycine or a fake pill before bed, then rated sleepiness and fatigue using scales and questionnaires, and did computer tests for alertness and focus.

Glycine cut fatigue by 20-30% on the first day and sped up reaction times in alertness tests on days 1 and 3. In rats, glycine raised levels of two brain chemicals—arginine vasopressin (a hormone that helps control body rhythms) and vasoactive intestinal polypeptide (a messenger that aids sleep signals)—in the brain's "body clock" area during daytime, without changing melatonin or core clock genes.

Try 3g glycine before bed to fight tiredness from short sleep.