Figure 6.

Simultaneous profiles of plasma total cortisol (solid line) and saliva free cortisol (dashed line) in two healthy young adults who were each submitted to blood sampling via an indwelling catheter at 20-minute intervals from 9 AM to midnight and provided a saliva sample at the time of each blood sampling. Caloric intake was exclusively in the form of a glucose infusion at a constant rate of 5 g/kg/24 h. Simultaneous levels of plasma cortisol and saliva cortisol were highly correlated in both individuals (r: Pearson correlation coefficient). [Unpublished illustration of data included in A. Guyon et al: Adverse effects of two nights of sleep restriction on the hypothalamic-pituitary-adrenal axis in healthy men. J Clin Endocrinol Metab. 2014;99(8):2861–2868 (117), with permission. © The Endocrine Society.]