Figure 2. Average concentrations of cortisol (dashed lines) and growth hormone (GH, solid lines) during the first and second halves of nocturnal sleep in young men after a day without exercise (left), after moderate exercise during the preceding afternoon (40 km of biking, middle), and after intense distress (120-150 km of biking, right). Per cent values of hormonal concentrations are shown with the nightly average concentration set to 100 %. Note, intense exercise abolishes the typical early sleep endocrine pattern with minimum cortisol concentrations and maximum GH concentrations. Data are from Kern et al. 1995.