Fatigue and leptin plots for healthy controls. Left panes: Self-reported fatigue severity (solid blue line) "tracks" with serum leptin concentration (dotted green line) over the 25-day protocol in one healthy control (#19). Right panes: Scatter plots illustrate the strength of association between self-reported fatigue severity and serum leptin concentration. The data have been Z-score transformed to fit on the same scale. The mean AM and PM fatigue scores are displayed.