Birdsall TC. 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Altern Med Rev. 1998 Aug;3(4):271-80.

Meyers, S. Use of neurotransmitter percursors for treatment of depression. Altern Med Rev. 2000 5(1): 64-71.

Sano I. L-5-hydroxytryptophan-(L-5-HTP) therapy. Folia Psychiatr Neurol Jpn 1972;26:7-17.

Poldinger W, Calanchini B, Schwarz W. A functional-dimensional approach to depression: serotonin deficiency as a target syndrome in a comparison of 5-hydroxytryptophan and fluvoxamine. Psychopathology 1991;24:53-81.

Meoli, AL, Rosen, C, Kristo, D et al. Oral nonprescription treatment for insomnia: An evaluation of products with limited evidence. Journal of Clinical Sleep Medicine, Vol. 1, No. 2, 2005.

Shell W, Bullias D, Charuvastra E, May LA, Silver DS. A randomized, placebo-controlled trial of an amino acid preparation on timing and quality of sleep. Am J Ther. 2010 Mar-Apr;17(2):133-9.

Zarcone V, Kales A, Scharf M, Tjiauw-Ling T, Simmons J, Dement W. Repeated ingestion of 5-hydroxtryptophan. Arch Gen Psychiatry. 1973;28:843-86.

Monograph: Vitamin B6 (pyridoxine; pyridoxal 5'-phospahte). Alt Med Rev. 2001; 6(1): 87-92.

McCarty MF. High-dose pyridoxine as an 'anti-stress' strategy. Med Hypotheses. 2000 May;54(5):803-7.

Baldewicz T, Goodkin K, Feaster DJ, Blaney NT, Kumar M, Kumar A, Shor-Posner G, Baum M. Plasma pyridoxine deficiency is related to increased psychological distress in recently bereaved homosexual men. Psychosom Med. 1998 May-Jun;60(3):297-308.

Inagawa K .et al. Subjective effects of glycine ingestion before bedtime on sleep quality. Sleep and Biological Rhythms.2006; 4(1): 75-77.

Yamadera W. et al. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep and Biological Rhythms.2007; 5(2): 126-131.

Bannai M, et al. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Front Neurol. (2012)

Startz T, Samborski W, Hrycaj P, et al. Seroto- nin concentration in serum of patients with generalized tendomyopathy (fibromyalgia) and chronic polyarthritis. Med Klin 1993;88:458-462.