What is the best match for Jet Lag?

Jet lag is primarily associated with disruptions in the body’s circadian rhythm, which regulates sleep-wake cycles and is influenced by external cues like light. Melatonin is a hormone produced by the pineal gland in response to darkness, signaling the body that it is time to sleep. When traveling across multiple time zones, the natural production of melatonin can be misaligned with the new environment, leading to symptoms of jet lag such as fatigue, insomnia, and disorientation. The correct answer emphasizes the importance of melatonin in regulating these rhythms, particularly when the body is adapting to a new time zone.

Other options do not specifically pertain to the disruption of sleep cycles caused by traveling. While growth hormone (GH) levels can have various effects on the body, they do not directly correlate with the physiological processes involved in jet lag. Similarly, cortisol's role is more related to stress response and inflammation rather than establishing sleep-wake cycles. Thus, the association of melatonin production with the body's normal rhythm makes it the most relevant match for understanding jet lag.