L-Tryptophan

Interval therapy with L-tryptophan in severe chronic insomniacs. A predictive laboratory study.
Schneider-Helmert D.
Int Pharmacopsychiatry. 1981;16(3):162-73.

 Interval therapy is the concept of intermittent applications with drug-free intervals, based on the observation that in many cases L-tryptophan has the best effects on disturbed sleep during the drug-free interval after-short-term application. This concept was formulated as an experimental hypothesis to be tested in the sleep laboratory in a predictive, double-blind design, comparing a 4-night placebo period following repetitive 3 X 2 g L-tryptophan application with baseline. All patients,severe chronic insomniacs, 5 males and 3 females (mean age 38.4 years) improved significantly at the predefined level of 0.05. Analyses of the polygraphic recordings proved highly significant sleep improvements in the parameters that are indicators of insomnia. No side effects were seen. It can be concluded that the interval therapy with L-tryptophan is a potent treatment for chronic  primary insomnia. PMID: 7033160

  Tryptophan depletion and its implications for psychiatry.
Bell C, Abrams J, Nutt D.
Br J Psychiatry. 2001 May;178:399-405.

 Over the past 10 years the technique of tryptophan depletion has been used increasingly as a tool for studying brain serotonergic systems. To review the technique of tryptophan depletion and its current status as a tool for investigating psychiatric disorders. Tryptophan depletion produces a marked reduction in plasma tryptophan  and consequently brain serotonin (5-HT) synthesis and release. In healthy volunteers the effects of tryptophan depletion are influenced by the characteristics of the subjects and include some mood lowering, some memory impairment and an increase in aggression. In patients with depression tryptophan depletion tends to result in no worsening of depression in untreated subjects but a relapse in those who have responded to antidepressants (particularly serotonergic agents). In panic disorder the results are similar. The findings that tryptophan depletion produces a relapse of symptoms in patients with depression and panic disorder who have responded to treatment with antidepressants suggests that enhanced 5-HT function is important in maintaining response in these conditions. PMID: 11331552

  Treatment of severe chronic insomnia with L-tryptophan: results of a double-blind cross-over study.
Demisch K, Bauer J, Georgi K, Demisch L.
Pharmacopsychiatry. 1987 Nov;20(6):242-4.

 Thirty-nine subjects with chronic insomnia were treated with L-tryptophan (L-TRP) in a double-blind, cross-over study. Instead of a placebo, a very low dose of 0.04 g L-TRP was used. The subjects suffered from a sleeping disorder classified as “psychophysiological, persistent”. In the subgroup taking the full L-TRP (2 g) dose first, there was a significant difference between the treatment period with the full L-TRP dose and the ineffective dose (placebo). If the placebo was given first, however, there was no significant difference between the two treatment periods. It is suggested that psychological factors are responsible for the diverging results in the two subgroups of patients. On the basis of subjective ratings, it appears that L-TRP is effective in promoting sleep in cases of chronic insomnia. PMID: 3432357