Insomnia is a common problem for adults in Western society. This is surprising because modern life is hectic and tiring and therefore it would be expected that sleep should not be a problem with such a lifestyle. However, increasingly insomnia is associated with Western lifestyle habits. There have been many studies that have investigated the reasons for such a widespread inability of so many to sleep well. The general consensus of these studies are that the Western lifestyle and diet is directly responsible for disruption of sleep patterns. In particular, the stressful life, lack of exhaustive exercise and poor diet may contribute to disrupted sleep patterns. Of these stress and a lack of exercise may be particularly problematic. Stress causes the release of stress hormones including glucocorticoids and adrenaline, and this can cause significant disruption to normal sleep cycles. Exercise, although a form of stress itself can reduce circulating levels of glucocorticoids and adrenaline as adaptation to exercise stress occurs.
L-tryptophan is an essential amino acid that is required for the production of serotonin. Serotonin has a number of important functions in the central nervous system, one of which is as a substrate to melatonin, the primary regulating hormone of the sleep wake cycle. Dietary L-tryptophan may increase serotonin and melatonin production in the brain, and this may allow diets high in L-tryptophan to induce sleep. Supplemental L-tryptophan is available, and studies have investigated the effects of L-tryptophan supplement in the gram dosage for its ability to induce sleep. For example, in one study1, researchers assessed the ability of L-tryptophan to alter daytime electroencephalogram (EEG) patterns and induce drowsiness in healthy subjects. The results of the study showed that L-tryptophan changes EEG frequency patterns such that alpha and theta waves, associated with increased relaxation and calmness, increased significantly in frequency and duration with increasing L-tryptophan plasma levels.
L-tryptophan also increase sleep latency (the period between waking and sleeping) without affecting the quality of nap sleep during the day. The authors suggested that these results provide good evidence for the relaxing and sleep inducing effects of L-tryptophan. The dosages used in this study were between 1 and 15 grams, that latter being a very large dose. However other studies have found similar results with smaller doses in the 1 to 3 gram range. A metabolite of L-tryptophan, 5-hydroxytryptophan, is also available, and may have similar effects. Like L-tryptophan, 5-hydroxytryptophan enters the brain where it increases levels of serotonin and melatonin, thus having a very similar effect on the quality and duration of sleep. Griffonia simplicifolia, a shrub native to Africa, is the source of commercially available 5-hydroxytryptophan, classifying the compound as a herb. Serotonin and melatonin levels can also be increased through consumption of carbohydrate foods.
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