Boyce P M
Am J Psychiatry. 1985 Jan;142(1):125-7. doi: 10.1176/ajp.142.1.125.
The daytime and nighttime levels of 6-sulphatoxy melatonin, a metabolite of melatonin, were measured in eight melancholic patients. Three patients did not show a marked nocturnal increase in 6-sulphatoxy melatonin excretion. The author discusses the relationship between melatonin and melancholia.