Sleep support evidence brief
Glycine is an amino acid sold for sleep quality, relaxation, and sometimes connective-tissue support. Sleep claims usually involve bedtime dosing rather than daytime stimulation.
Small human sleep and next-day fatigue studies suggest glycine can help some users feel better rested.
Small 3 g bedtime crossover trials improved subjective sleep quality, daytime fatigue, or next-day alertness.
Human sleep studies often use about 3 g before bed; collagen or protein intake is not equivalent.
Reasonable as a sleep-adjacent ingredient. Muscle-building, tendon-repair, or direct performance claims need separate evidence.
Source Drawer
The score reflects evidence that the supplement does its stated job. Some jobs are direct, such as strength, endurance, or recovery; others are indirect, such as sleep, mood, appetite, or health support. A real effect can still receive a cautious practical rating when dose, safety, product quality, or audience fit remain uncertain.
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