Circadian Rhythm and Hypothalamus

Circadian rhythms are derived from the Latin word circa Diem that means around the day. The rhythms are biological processes that occur regularly on approximately a twenty-four-hour cycle. This system helps an individual to move from wakefulness to sleep, and back to wakefulness. Several other bodily functions that include body temperature, hormone production, and blood pressure, and some other parts also follow circadian rhythms. For instance, the cycle that is between wakefulness and sleeps in our body is a circadian rhythm. The cycle of circadian rhythms is a complex one that involves a variety of behaviors. For instance, sleepiness occurs not just in the evening, but throughout the day in regular patterns, with most of us getting drowsy in mid-afternoon regardless of whether an individual has eaten such as a heavy lunch. The suprachiasmatic nucleus (SCN) within our brain regulates circadian rhythms located in the hypothalamus. In the control of circadian rhythms, the relative amount of light and darkness, which varies with the seasons of the year, also plays a role. The SCN controls melatonin secretion, a hormone that makes a person sleepy. People also experience the seasonal affective disorder, which is a form of severe depression in which feelings of despair and hopelessness increase during the winter and lift during the rest of the year. The disorder appears to be the consequence of winter days’ clarity and darkness. Daily exposure to bright lights is sometimes sufficient to improve the mood of people with this disorder. Circadian rhythms also explain the phenomenon of jet lag that is caused by flying through multiple time zones. For instance, Pilots as well as others who must work on constantly changing time shifts fight with the internal clocks that result in fatigue, irritability, and, even worse, outright error. Circadian cycles are maintained by temporal stimuli in the environment on a once-every-24-hours cycle. The most important of the cues for the regulation of mammalian circadian rhythms is the daily cycle of light and dark.