Figure 4:Leptin rhythms evaluated in six healthy men, by collecting blood every 7 minutes during 24 hours. a, number of statistically significant leptin pulses assessed by Cluster (magenta) and Detect (blue). b, pulse height assessed with Cluster (x-axis) and Detect (y-axis) (r=0.9998; P < 8 x 10-8, Pearson correlation). c, assessment of leptin pulse numbers in data sets corresponding to sampling every 7, 14, 21, 28, 35, 42, 49 and 56 minutes, assessed by Cluster. d, comparison of leptin levels and pulse parameters in two Caucasian women (A, normal weight; B, obese). Reprinted by permission from Macmillan Publishers Ltd: Nature Medicine, ref. (25) , copyright 1997.