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Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

16.10.2010

Sleep aid L-tryptophan works at daytime too

Taking L-tryptophan before going to bed reduces the time you need to fall asleep. The amino acid also works if you want to take a nap during the day, researchers at the American Naval Health Research Center discovered in the early eighties.

Scientists discovered in 1967 that tryptophan, an amino acid found in protein-rich foods, works as a sleep aid. In medical circles they call it an hypnotic or soporific substance. How it works is still not clear. The diagram here shows how the body converts tryptophan into related compounds, two of which could cause sleepiness: serotonin and melatonin.

The scientists at the Naval Health Research Center were not interested in the sleep mechanism itself, however. The Americans just wanted to know whether they could use tryptophan to improve their soldiers’ condition. Sleep keeps us fit, but in crisis situations soldiers have little time to sleep. Substances that induce asleep would help soldiers to make more efficient use of the short periods available to them for sleep.

The researchers gave 15 men and 5 women 4 g L-tryptophan, once at 9 o'clock in the morning and once at 1 o'clock in the afternoon. The dose is on the high side, but previous studies suggested that you need amounts like this for inducing sleep during the day. They repeated the experiment using a placebo.

The amino acid level peaks about 75 minutes after ingesting the L-tryptophan. That's why the subjects went to lie down in a darkened room an hour after taking the pills.

The amount of time the subjects took to fall asleep halved when they took the supplement. Other values did not change significantly.

The researchers suspect that the sleep inducing effect of tryptophan has to do with serotonin. Extrapolating from what was already known about the effects of serotonin, the researchers suspect that tryptophan does not work under all conditions.

Serotonin has a stimulatory effect in people who are restless. A high level of serotonin in the brain only has a calming effect if the surroundings are also tranquil. 'Tranquil' is not a characteristic of crisis conditions, and soldiers in war situations are more likely to be restless. But that doesn't mean that the study is not interesting for ordinary people who for whatever reason want to sleep better.

You can find the original research report in its entirety [here].

Source:
Electroencephalogr Clin Neurophysiol. 1983 Jun;55(6):652-61.

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