amino acid · for insomnia
Glycine
Lowers your core temperature slightly, which is one of the signals that starts sleep.
Say that in clinical terms
Glycine acts on NMDA receptors in the suprachiasmatic nucleus to lower core body temperature, a key signal for sleep initiation. It also increases serotonin levels in the prefrontal cortex and enhances slow-wave sleep quality.
How strong is the research?
3 papers read, 3 supporting.
Who was studied: Japanese adults who said they slept badly, without a formal insomnia diagnosis.
How much to take
daily, 1 hour before bed
3000 mg
Take 3g before bed. Can be dissolved in water or taken as capsules. Generally very well tolerated.
Before you take it
- No NIH ODS or IOM/NAM Tolerable Upper Intake Level (UL) has been established for glycine; it is absent from all NIH ODS fact sheets.
- FDA includes glycine on its GRAS (Generally Recognized as Safe) list for food use. Doses up to 90 g/day have been administered in psychiatric research trials without serious adverse events; GI discomfort (nausea) is the most commonly reported side effect at high doses.
- A pharmacodynamic interaction between supplemental glycine and clozapine (antipsychotic) has been documented at high psychiatric doses (30-60 g/day): glycine's therapeutic efficacy for schizophrenia negative symptoms is less consistent when patients are co-administered clozapine, likely because clozapine itself occupies the NMDA receptor glycine-binding site. This interaction has not been studied at 3 g supplemental doses; the clinical relevance at that dose is unknown but theoretically possible.
- Formal supplemental safety data in pregnant and nursing women are lacking; standard caution applies.
- At the 3 g/day dose used in sleep studies, tolerability has been described as good with no serious adverse effects reported across published trials.
When to take it
Best taken: evening
What we make of it
The only human sleep-lab trial, and every author worked for the manufacturer.
The detail
This is the one human trial with proper sleep-lab measurements. Participants were dissatisfied with their sleep rather than diagnosed with insomnia, and all the authors had documented ties to the company producing the ingredient.