Everstack Evidence

Glycine, L-theanine and apigenin: the evening trio

Glycine and L-theanine: small randomized trials (C). Apigenin: mostly mechanistic and observational work (D). We show the weakest link openly.

Published 2026-10-14Sources checked 2026-10-142 sourcesEverstack research teamHow we work

Editorial section. Research summaries are not product claims and contain no product links or offers. A summary is never proof that any product works.

The question

What is the human evidence for each ingredient in our PM stack?

Study design

Glycine 3 g crossover trial with polysomnography (2007). L-theanine 200 mg/day, 4-week randomized placebo-controlled trial in 30 healthy adults (2019). ^[1][2]

What they found

Glycine improved subjective sleep quality and next-day alertness in small groups. L-theanine improved self-reported stress-related measures and sleep quality scores versus placebo. ^[1][2]

Limitations

Small samples and short durations. No trial has tested this exact combination.

What this does not mean

A combination is not proven just because each part has some data. We will update this page as better studies appear.

Sources

1. Yamadera W et al. Sleep Biol Rhythms. 2007;5:126-131. doi.org/10.1111/j.1479-8425.2007.00262.x
2. Hidese S et al. Nutrients. 2019;11(10):2362. doi.org/10.3390/nu11102362

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