Amino Acids for Sleep
After melatonin and magnesium, the amino acids are the most-discussed sleep supplements in our data. They work in different ways and owners describe them differently.
| Supplement | Score | Owner comments | Unwanted effects |
|---|---|---|---|
| Glycine | 3.9 | 281 | 10% |
| L-theanine | 3.8 | 333 | 14% |
| GABA | 2.9 | 47 | 25% |
| Taurine | 3.5 | 59 | 11% |
| L-tryptophan | 3.6 | 27 | 6% |
| 5-HTP | 3.7 | 37 | 0% |
| Inositol | 3.6 | 14 | 0% |
Glycine
Japanese studies gave about 3 g of glycine before bed and measured subjective sleep quality and next-day sleepiness.[PubMed][PubMed] Owners mostly take the powder and describe deeper sleep more than faster sleep.
L-theanine
A 2019 randomized trial measured stress-related symptoms and sleep with 200 mg a day, and a 2025 meta-analysis pooled theanine sleep trials.[PubMed][PubMed] On Reddit it is often described as calming rather than sedating.
GABA
How much GABA taken by mouth reaches the brain is debated; a 2018 trial gave GABA from fermented rice germ to people with insomnia symptoms.[PubMed] It has one of the lower owner scores in our data.
Tryptophan and 5-HTP
Both are building blocks for serotonin and melatonin.[PubMed][PubMed]
Serotonin caution: do not combine 5-HTP or L-tryptophan with SSRIs, SNRIs, MAOIs, triptans, tramadol or other serotonergic drugs without a doctor; the combination can cause serotonin syndrome.[PubMed]
Compare: L-theanine vs glycine · L-theanine vs GABA · 5-HTP vs L-tryptophan.
You can also compare all rated sleep aids on one page. For quick shortlists by sleep problem, see which sleep supplements Reddit rates highest. Before starting, check sleep supplement safety and interactions.