The daily pace and technology of modern life has more to do with a civilized notion of productivity than our ancient, inborn circadian rhythm. But although we may have found ways to work around the rising and setting of the sun through innovation and shear will, the biological clock that we evolved to answer to still rules our bodies.
Our inherent adherence to a circadian rhythm can be traced to something in our cerebral cortex called the suprachiasmatic nucleus, or, the master clock. In most of us the master clock interacts closely with the optic nerve in response to the amount of light that our brain registers, establishing the basis of a biological clock that is sensitive to a diurnal, circadian rhythm.
There are complex processes that underlie the sleep-wake cycle that dominate the circadian rhythm. Different hormones and compounds in our body rise and fall over a 24-hour cycle, depending on whether it’s day or night. Melatonin and cortisol are two of the major hormones that are keeping you in tune with your circadian rhythm, while a collection of genes called CLOCK genes respond to different inputs throughout the day to regulate your mood, hunger, and body temperature.
Melatonin, for one, kicks into gear when the lights go down, chemically lulling our bodies to sleep. That’s why taking melatonin before a transcontinental flight can help stave off jet lag. It signals to your body that it’s time to sleep and will hopefully give you a decent, restful slumber until you land at your destination, helping you feel more attuned to the “morning,” even if your biological clock is still thinking you’re in the city of your departure.
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