Circadian rhythm fatigue is a result of disruption to which of the following biological processes?

• A. The body's internal clock regulating sleep-wake cycles
• B. The digestive system's processing of nutrients
• C. The cardiovascular system's regulation of blood pressure
• D. The immune system's response to pathogens

Answer: (A)

Verified step by step guidance

1. Identify the key term in the question: 'circadian rhythm fatigue.' This term relates to a biological process that affects alertness and sleep patterns.
2. Understand that circadian rhythms are natural, internal processes that regulate the sleep-wake cycle and repeat roughly every 24 hours.
3. Recognize that fatigue caused by disruption to circadian rhythms is linked to the body's internal clock, which controls when we feel awake and when we feel sleepy.
4. Eliminate other options by considering their primary functions: the digestive system processes nutrients, the cardiovascular system regulates blood pressure, and the immune system responds to pathogens—none of which directly control sleep-wake cycles.
5. Conclude that circadian rhythm fatigue results from disruption to the body's internal clock regulating sleep-wake cycles.