cortisol

Prolonged stress elevates cortisol levels, which can suppress immune function.长期的压力会升高皮质醇水平，从而抑制免疫功能。

Cortisol follows a diurnal cycle, peaking in the morning and declining through the day.皮质醇遵循昼夜节律，在早晨达到峰值，并在全天内逐渐下降。