Do plasma melatonin concentrations decline with age? Germaine Cornélissen, PhD, Franz Halberg, MD, Naoto Burioka, MD, Federico Perfetto, MD, Roberto Tarquini, MD, Earl E Bakken, DSc  The American Journal of Medicine  Volume 109, Issue 4, Pages 342-344 (September 2000) DOI: 10.1016/S0002-9343(00)00515-5

Figure In data taken from a published graph (1), a smaller circadian amplitude can be demonstrated in older subjects when the data have been log10-transformed, but not when they are expressed in original units. The American Journal of Medicine 2000 109, 342-344DOI: (10.1016/S0002-9343(00)00515-5)