Figure 2.

Fingernail melatonin concentrations are able to determine the gradual decrease of melatonin production over the life-span. (A) Gender stratified differences in the established age ranges: range 5–20, females (n = 6) and males (n = 5); range 21–40, females (n = 11) and males (n = 5); range 41–60, females (n = 14) and males (n = 15); range > 60, females (n = 19) and males (n = 9). (B) Differences in age ranges when considering both genders together: range 5–20 (n = 11); range 21–40 (n = 16); range 41–60 (n = 29); range > 60 (n = 28). (C) Correlation between fingernail melatonin concentrations and age. ** Statistically significant differences (p < 0.01).