The biological clock modulates the human cortisol response in a multiplicative fashion

Human cortisol levels follow a clear circadian rhythm. We investigated the contribution of alternation of sleep and wakefulness and the circadian clock, using forced desynchrony. Cortisol levels were best described by a multiplication of a circadian and a wake-time component. The human cortisol response is modulated by circadian phase. Exposure to stress at an unnatural phase, as in…

Short-wavelength attenuated polychromatic white light during work at night: limited melatonin suppression without substantial decline of alertness

Van de Werken, M., Giménez, M. C., de Vries, B., Beersma, D. G. M., & Gordijn, M. C. M. Short-wavelength attenuated polychromatic white light during work at night: limited melatonin suppression without substantial decline of alertness. Chronobiology International, 30(7), 843–854. (2013).