Does taking glycine help you sleep better?
Glycine shows tentatively positive signals, but the evidence is thin and the only direct human study comes from the manufacturer itself. Anyone who wants to try it would be wise to view it as a complement to good sleep habits, not a replacement.
Glycine (3 grams) taken before bedtime improved subjective sleep quality in people with insomnia complaints in a Japanese study. One caveat: that study was conducted by Ajinomoto, the manufacturer of glycine supplements. The exact size of the effect is not reported in the published abstract, and independent replication in larger groups is lacking.
A plausible biological mechanism does exist. Glycine activates inhibitory nerve receptors in the brain that play a role in the sleep-wake cycle. Animal studies also show that oral glycine lowers core body temperature and increases skin blood flow. A falling core body temperature is a well-known step in the process of falling asleep. This mechanistic line of evidence is plausible, but animal results are no guarantee of the same effect in humans.
A small RCT (16 participants) found beneficial effects on sleep onset latency, total sleep time and sleep efficiency, but that involved a combination supplement also containing tryptophan, magnesium, tart cherry and L-theanine. Which component made the difference therefore cannot be determined. Glycine alone cannot be isolated from this study.
Broader reviews mention glycine as a possible supplement for sleep problems, but regard the evidence as limited and explicitly position it as a complement to good sleep habits, not a replacement. How glycine interacts precisely with other sleep-related systems (such as melatonin) remains unclear for the time being.
Safety data do not appear in the available abstracts. For an amino acid that the body produces itself and that is also found in protein-rich foods, a dose of 3 grams is probably low-risk, but the absence of safety information in the source means this cannot be extrapolated to long-term use or specific health conditions.
All claims are based on a limited number of studies, of which the most direct human study was funded by the manufacturer. Independent large RCTs are lacking. Combination studies do not allow any conclusion about glycine on its own.
Does magnesium glycinate help you sleep better?
Magnesium may offer some benefit for sleep in certain people who are deficient or have a medical condition, but this has not been demonstrated for healthy people without a deficiency. If you have had poor sleep for years, first discuss with your doctor whether other causes may be involved.
Does apigenin help you sleep better?
There is currently no evidence that apigenin as a supplement meaningfully improves sleep in humans. Animal research is promising, but the only randomised study in humans showed no effect, so caution is warranted.
What can I do to sleep better?
CBT-I is the most powerful approach for persistent sleep problems; if you do not have access to it, ask your general practitioner about a shorter behavioural treatment of four sessions. Fixed sleep times, less caffeine and alcohol in the evening, and regular exercise are the best-supported self-help steps.
Does CBD oil help you sleep better?
There is currently too little good research to say that CBD oil genuinely helps with sleep problems; if you suffer from them, there are better-supported options to discuss with your doctor.
Does creatine affect your sleep?
Creatine may improve how you experience your sleep, but objective measurements show no effect. The research is based on dozens of participants and the results are contradictory; do not use it as a sleep aid.
Does pain make me sleep worse, and what can you do about it?
Pain and poor sleep reinforce each other, with sleep deprivation typically aggravating pain more than the other way around. The treatment with the strongest evidence is cognitive behavioural therapy for insomnia (CBT-i), which demonstrably improves sleep, although the pain does not automatically disappear as a result.