Which hormone is commonly disrupted due to poor sleep quality?

Melatonin is the correct answer because it plays a crucial role in regulating the sleep-wake cycle in the body. It is primarily produced in the pineal gland and is influenced by the body's exposure to light; its secretion typically increases in response to darkness, promoting sleepiness. When sleep quality is poor, melatonin production can be disrupted, leading to difficulties in falling and staying asleep. This can create a cycle where inadequate sleep further impairs melatonin secretion and the ability to achieve restorative sleep.

Cortisol, which is often associated with stress, can also be affected by sleep patterns, leading to a disruption in its natural circadian rhythm; however, its primary role is not focused solely on regulating sleep. Adrenaline is mainly involved in the body's fight-or-flight response and while elevated levels can result from poor sleep, it is not primarily viewed as a sleep-regulating hormone. Serotonin is a neurotransmitter that contributes to the regulation of mood and can affect sleep, but it is not specifically a sleep hormone like melatonin. Thus, the direct connection between melatonin levels and sleep quality clearly establishes it as the hormone most commonly disrupted by poor sleep quality.