Questions & Answers

The 24-hour (diurnal) rhythm of our body such as the sleep-wake cycle is regulated by the hormone
A. Calcitonin
B. Prolactin
C. Adrenaline
D. Melatonin

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Hint:Chemical messengers that are directly secreted into the blood are called hormones, which transport them through their roles to organs and tissues. Diurnal cycles are a circadian rhythm that is synchronized with the day/night cycle, and there are several forms of hormones that work on various aspects of body functions and processes.

Complete answer:Calcitonin is a hormone produced by the parafollicular cells of the thyroid gland in humans (C-cells). In comparison to the action of parathyroid hormone, calcitonin is involved in helping to control calcium and phosphate levels in the blood.
Prolactin is a hormone that sits at the bottom of the brain, created by the pituitary gland. Prolactin causes breasts to grow and develop and after a baby is born, causes milk to be produced. In their blood, both men and women typically have small quantities of prolactin. Prolactin, also known as lactotroph, is a protein is better known for its function in allowing milk to be produced by animals, usually females.
Adrenaline is a hormone and a drug, also known as epinephrine. Adrenaline is typically formed in the medulla oblongata by both the adrenal glands and a limited number of neurons, where it serves as a neurotransmitter engaged in the control of visceral functions.
Melatonin is a hormone in the brain secreted by the pineal gland. Melatonin, primarily released by the pineal gland, is a hormone that regulates the sleep-wake cycle. Melatonin is involved in controlling the circadian rhythms of physiological functions in animals, including sleep timing, control of blood pressure, seasonal reproduction, and many others. It is also used in the short-term treatment of insomnia, such as jet lag or shift work, as a dietary supplement and is typically taken by mouth.

So,'melatonin' is the right answer.

Note: Desynchronizing between internal sleep-wake cycles and the pattern of light-darkness is the source of sleep disruptions of the circadian rhythm. Patients are typically tired, highly sleepy throughout the day, or both, usually when the clock is reorganized. The diagnosis is medical. Treatment varies depending on the cause.