Figure 5. Diurnal morning and evening variations of salivary cortisol in a 23-year-old normal-weight male firefighter.

Panel AM: Diurnal variation in morning salivary cortisol showing a trendline of significant positive slope (R²=0.91). Panel PM: Diurnal variation in evening salivary cortisol showing a trendline of significant negative slope (R²=0.78). Subject characteristics: height 70 in, weight 163 lbs, body mass index 23 kg/sq m, waist-hip ratio 0.88, pulse 80/min, blood pressure 132/58 mmHg, pulse pressure 74 mmHg, years in fire service 1 y, hours worked prior to shift 144 h, hours worked in past days 408 h.