There is plenty of good research on the benefits of glycine for anti-aging (1), sleep (2), restoring youthful glutithione levels (3), etc. I've been taking 3g every day before bed, and I do sleep noticeably better when I take it.
However, after taking it like this for about 2 or 3 weeks straight, I start to get extreme daytime sleepiness. Even after a perfect 8 hours of sleep, I'm groggy all day and can't wait to crawl in bed at night. I'm not 100% sure it's the glycine, but I'm 90% sure. The only other real possibilities are some transient sickness, or worse than usual allergies. I've just finished my 3rd try of supplementing with glycine, and each time I've have to quit for a while just to be able to function like a normal person again. I think the health benefits are pretty clear cut, so I'd like to continue with it, but I can't handle the fatigue. The thing is, I can't find any study or even an anecdotal report that talks about fatigue associated with glycine. The glycine sleep study even reported an improvement in daytime sleepiness due to the better sleep, so I'm baffled.
Does anyone else take glycine regularly, and have you experienced fatigue?
I've taken it but not consistently enough to notice the above. I didn't know that about the glutathione, so thx!
Check this out:http://www.ncbi.nlm.nih.gov/pubmed/21414089
"Oral administration of glycine increases extracellular serotonin but not dopamine in the prefrontal cortex of rats."
Glycine, one of the non-essential amino acids, has been reported to be effective in reducing negative symptoms of schizophrenia. Recently, we found that glycine improves subjective sleep quality in humans.
The aim of this study was to investigate the effects of oral glycine administration on endogenous 5-hydroxytryptamine (5-HT) and dopamine in the prefrontal cortex (PFC) of living rats.
Microdialysis probes were inserted stereotaxically into the rat prefrontal cortex. Cortical levels of 5-HT and dopamine were measured following oral administration of 1 or 2 g/kg glycine, 2 g/kg d-serine, or 2 g/kg L-serine.
RESULTS:Both glycine and d-serine significantly increased extracellular 5-HT levels for 10 min
, whereas dopamine levels remained unchanged. L-serine, in contrast, had no significant effects on 5-HT levels.
It is possible that the increase in 5-HT in response to glycine and d-serine was mediated by N-methyl-D-aspartate receptors. The transient increase in 5-HT in the PFC might be associated with the alleviation of negative symptoms in patients with schizophrenia and the amelioration of sleep quality in patients with insomnia."