Improve your sleep with glycine, and your memory will work better too
Recently we wrote about a Japanese study from 2006 in which supplementation with 3 g glycine improved the quality of sleep without side effects. The subjects felt more clear-headed the next day instead of being drowsy. Researchers at Ajinomoto and Jikei University in Tokyo went a step further in a study they did in 2007. They discovered that memory functions better after glycine-improved sleep.


Glycine [structural formula shown above right] is a non-essential amino acid. It's the smallest amino acid, which the body makes by converting serine, but it's also found in food.Gelatin for example consists of 22-25 percent glycine. If you want to consume 3 g glycine, and don't have glycine supplements available, then 12-14 g gelatin would do the trick.
Animal studies have shown that glycine supplementation is safe. The LD50 – the single dose at which half of a group of rats dies – is 7.9 g glycine per kg bodyweight. That's high.
The researchers published in 2007 in Sleep and Biological Rhythms the results of an experiment in which 11 subjects aged 30-57 participated. On one occasion the subjects took 3 g glycine an hour before hitting the sack; on the other occasion they took a placebo.

The next day the participants reported that they had slept better after taking the glycine supplement. To put it more precisely: the subjects felt they had fallen asleep more quickly and had woken less often during the night after taking glycine. During the day following a night of glycine-aided rest, the subjects felt more alert.

The researchers monitored the sleeping behaviour of the subjects, and noticed that the glycine supplementation had a subtle but positive effect on the sleep pattern. The subjects slept more quietly as a result of the amino acid [Awake/Microarousal was less] and did indeed fall asleep more quickly [Stage 1 was shorter].

The researchers also discovered that the glycine-enhanced sleep also led to an improvement in memory function. The subjects were given a test in which they had to remember letters or numbers that they had seen previously on a computer screen.

"The importance of a good night's sleep is not in doubt", the Japanese conclude. "The use of chemical hypnotics is widespread, although they have well-known problems."

"Therefore there is a need for a safe and reliable sleep regulator for those occasions when sleep is disturbed. Our present results suggest that glycine produces subjective and objective improvement of sleep quality and leads to a natural sleep pattern, including an early appearance of slow wave sleep and maintenance of REM sleep."
Sleep and Biological Rhythms 2007; 5: 126-31.