Which physiological response is triggered by darkness alongside melatonin secretion?

Which physiological response is triggered by darkness alongside melatonin secretion?

• A. Increased core body temperature
• B. Vasodilation leading to warm extremities
• C. Elevated stress hormone levels
• D. Increased blood flow to the brain

Answer: (B)

Melatonin secretion is closely associated with the body’s circadian rhythms, primarily triggered by darkness. One of the physiological responses linked to melatonin and sleep is vasodilation, which can lead to warm extremities. When melatonin levels rise in response to darkness, the body prepares for sleep, and one of the mechanisms involved is the dilation of blood vessels, especially near the skin and extremities. This increased blood flow can help lower core body temperature as part of the process of initiating sleep, which promotes a sense of warmth in the hands and feet. In contrast, other options do not accurately capture the physiological response linked to melatonin secretion. Increased core body temperature is counterproductive to sleep initiation; elevated stress hormone levels are generally associated with stimulation and wakefulness rather than the relaxation induced by melatonin; and while blood flow to the brain is important for various functions, it is not specifically increased as a direct response to darkness and melatonin but instead is more complex and influenced by many factors.

Melatonin secretion is closely associated with the body’s circadian rhythms, primarily triggered by darkness. One of the physiological responses linked to melatonin and sleep is vasodilation, which can lead to warm extremities. When melatonin levels rise in response to darkness, the body prepares for sleep, and one of the mechanisms involved is the dilation of blood vessels, especially near the skin and extremities. This increased blood flow can help lower core body temperature as part of the process of initiating sleep, which promotes a sense of warmth in the hands and feet.

In contrast, other options do not accurately capture the physiological response linked to melatonin secretion. Increased core body temperature is counterproductive to sleep initiation; elevated stress hormone levels are generally associated with stimulation and wakefulness rather than the relaxation induced by melatonin; and while blood flow to the brain is important for various functions, it is not specifically increased as a direct response to darkness and melatonin but instead is more complex and influenced by many factors.