1. Nocturnal 6-sulfatoxymelatonin excretion in insomnia and its relation to the response to melatonin replacement therapy 
Damien Leger, MD, Moshe Laudon, PhD, Nava Zisapel, PhD 
The American Journal of Medicine 
Volume 116, Issue 2, Pages (January 2004)
DOI: /j.amjmed

2. Figure
Frequency distribution of nocturnal 6-sulfatoxymelatonin excretion in healthy volunteers (n = 30 [open squares], ages 20 to 35 years; n = 29 [open circles], ages ≥55 years) and in patients with insomnia aged ≥55 years (n = 517 [closed circles]).
The American Journal of Medicine  , 91-95DOI: ( /j.amjmed )