Question

What are circadian rhythms? Give two examples of circadian rhythms.

Explain how stress might affect cortisol circadian rhythms.

Answer 1

A circadian rhythm is a biological process that displays an endogenous, entrainable oscillation of about 24:hours. These rhythms are operate by a circadian clock, and they have been broadly observed in plants, animals, fungi, and cyanobacteria.

Menstrual cycle in women and the hibernation cycle in bears are two good examples of circadian rhythms.

cortisol plays a variety of roles in the human body. When we are chronically stressed, it is released in higher amounts throughout the day. The early light of morning cues the release of ACTH and thus the release of cortisol. Cortisol, in turn, causes ACTH production to shut down, along with giving us an energy boost that is much-needed when we are getting ready to start our day. When people are constantly stressed and producing high levels of cortisol throughout the day, this can cause this negative feedback loop to break down. Even when cortisol levels are high, ACTH production continues, creating yet higher cortisol levels throughout the day that can make it difficult to sleep.

this is not the only link between stress and your circadian rhythm. Cortisol also affects circadian genes in liver and adrenal cells. Constant triggering of these genes at random times of day in response to stress can make it so your body never knows exactly what time it is. This can lead to circadian dysregulation in which your body does not release hormones at the right times of the day to support a normal sleep-wake cycle.