GABA supplementation for improving sleep Original paper

Gamma-aminobutyric acid (GABA) is a neurotransmitter involved in relaxation, making it an important factor in the initiation and maintenance of sleep. Oral supplementation with GABA is sometimes recommended for improving sleep, but GABA is not known to readily cross the blood-brain barrier (i.e., sleep benefits of GABA supplementation are controversial).

This 4-week randomized controlled trial examined the effect of GABA supplementation on sleep among 64 adult participants (average age of 46) with insomnia who were assigned to take either 75 mg of GABA or a placebo.

The primary outcomes were sleep latency (i.e., time taken to fall asleep) and sleep efficacy (i.e., % of time in bed spent asleep), both of which were assessed using polysomnography (sleep monitoring, aka “a sleep study”). Other outcomes were sleep quality, insomnia severity, and excessive sleepiness, assessed using the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), and Epworth Sleepiness Scale (ESS), respectively.

The researchers reported the following:

• Sleep latency improved in the GABA group compared to the placebo group (GABA: 9 to 4.8 minutes; placebo: 6.5 to 8.2 minutes). Sleep efficacy was no different between groups.
• Total sleep time increased in the GABA group compared to the placebo group (GABA: 313.8 to 326.8 minutes; placebo: 306.5 to 295.5 minutes).
• Insomnia severity improved in the GABA group compared to the placebo group.
• Sleep quality and excessive sleepiness were no different between groups.

This study was published as a letter to the editor and therefore was not peer reviewed. The researchers wrote that “The demographics did not differ significantly between the two groups”, but very little of this demographic data was provided, making it difficult to confirm that the randomization process created appropriately balanced groups.

This study received funding support from Natural Way Co., Ltd., a GABA supplement manufacturer.

Although this study has shortcomings, its findings probably shouldn’t be discounted based on the idea that GABA does not cross the blood-brain barrier (and therefore can’t have an effect on sleep). For one thing, GABA receptors are present in a number of areas of the body (e.g, in the gut and certain immune cells), which are accessible to ingested GABA.^[1][2] It’s therefore possible that oral GABA could improve sleep via effects on these cells and tissues. Alternatively, whether ingested GABA actually can or cannot cross the blood-brain barrier in physiologically relevant amounts has not been conclusively demonstrated,^[3] (likely because such tests are extremely difficult^[4]).