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19.02.2013

Glycine boosts reaction time with lack of sleep

Glycine supplementation improves the quality of sleep and the day after a night of glycine-improved sleep your memory works better too, we wrote recently. According to a recent study done by the Japanese company Ajinomoto, glycine also helps when there is a shortage of sleep. The supplement improves reaction speed. So glycine may be an interesting supplement for gamers.

Glycine & sleep
There are hundreds of naturally occurring substances that improve the quality of sleep, but most of them make you more sleepy the next day and less alert. Glycine, an amino acid that is found in relatively large quantities in gelatin, is a favourable exception to this rule. Studies, which by the way as far as we know were all funded by producers of the product, have shown that glycine not only improves quality of sleep, but also makes the users more alert and less drowsy the next day. Mental performance improves as a result of glycine supplementation.

Human study
A small human study we found in Frontiers in Neurology suggests the same. In this study, the subjects were seven healthy men aged between 30 and 61. The researchers only let the men sleep for 5.5 hours a night for a period of three days so they were sleep deprived. Thirty minutes before they went to bed the men were given a placebo. After the first and the third night the researchers subjected their subjects to a battery of tests.

The researchers repeated the procedure, but gave the subjects 3 g glycine instead of the placebo. The figures below show what the effect of this was on the men's reaction times. The researchers measured this by doing a test in which the men sat at a screen, upon which three different symbols [A, B or C] could appear. When symbol A appeared the men had to press a button as quickly as possible.

The first figure shows the results for day 1, the second the results for day 3. The black circles represent the measurements taken during the glycine supplementation period. In both cases glycine improved the reaction time.

Animal study
The researchers also did an animal study. They gave 2 g glycine per kg bodyweight to rats, and observed that 2 hours later the production of the hormones vasopressin [AVP] and vasoactive intestinal polypeptide [VIP] in their brains – in their suprachiasmatic nucleus to be precise – increased by a factor of 4 and 3 respectively.

The researchers suspect that glycine interacts in the brain with the NMDA receptor, and via the receptor boosts the production of vasopressin. Vasopressin constricts blood vessels a little, thus ensuring that the urine contains less water. In theory this could raise blood pressure, but the researchers did not observe this.

The Japanese suggest that the measured effects of the glycine supplementation may be partly due to the increased production of vasopressin. How this works exactly they are not sure.

Source:
Front Neurol. 2012 Apr 18;3:61.

More:
Improve your sleep with glycine, and your memory will work better too 18.02.2013
Three grams glycine improves your sleep 17.02.2013