Namboodiri M A, Sugden D, Klein D C, Mefford I N
Science. 1983 Aug 12;221(4611):659-61. doi: 10.1126/science.6867734.
Daytime administration of 5-hydroxytryptophan to sheep elevated serum melatonin more than sevenfold within 2 hours. This suggests that administration of 5-hydroxytryptophan could be used as the basis of a clinical test of pineal function and that melatonin might mediate some clinical effects of 5-hydroxytryptophan.