Figure 3

Logistic transfer function graph. Logistic transfer function relating nocturnal melatonin suppression to the rectified circadian light stimulus (CS) from the model of human circadian phototransduction by Rea et al. [22]. Data from several studies using both narrow-band [34, 35] and polychromatic light sources [36–38] to induce nocturnal melatonin suppression were plotted as a function of CS. A logistic function from Zeitzer et al. [23] was used to fit the data yielding a regression coefficient (r²) for the transfer function equal to 0.82. Figure was adapted from Rea et al. [22].