Final answer:
Raymond is experiencing a disruption in his circadian rhythm due to working night shifts and facing difficulty adapting to the altered light-dark cycle which dictates sleep-wake patterns.
Step-by-step explanation:
Raymond's symptoms of extreme sleepiness during night shifts and difficulty sleeping during the day are most likely due to a disruption of his circadian rhythm. This disruption occurs because his biological clock, which is typically aligned with the external environment, is thrown off by his irregular sleep pattern. The circadian rhythm, generated by the suprachiasmatic nucleus (SCN), is sensitive to cues like light and dictates when we feel awake and when we feel sleepy. Working night shifts interferes with the normal light-dark cycle, leading to symptoms like insomnia and decreased alertness which indicates a misalignment between his internal clock and his work schedule.
Circadian rhythm is the 24-hour internal clock in our brain that regulates cycles of alertness and sleepiness by responding to light changes in our environment. Our physiology and behavior are shaped by the Earth's rotation around its axis.
At different times of the day, clock genes in the SCN send signals to regulate activity throughout the body. The SCN is highly sensitive to light, which serves as a critical external cue that influences the signals sent by the SCN to coordinate circadian rhythms in the body.