You know how you often feel tired and groggy in the afternoon? That’s your internal clock at work.
You might be more in tune with your work schedule than your body rhythm, but all of us are governed by a biological schedule. Circadian rhythm refers to the countless changes your body experiences over a 24-hour period. From your sleep-wake cycle to hormone production and daily fluctuations of alertness, circadian rhythms affect every aspect of your functioning.
The master internal clock that controls the different clocks throughout your body is a group of nerves in the hypothalamus called the suprachiasmatic nucleus (SCN). Each morning, light enters your eyes and travels along the optic nerve to signal to the SCN that it’s time to start the day’s circadian cycle.
For thousands of years, humans organized their days around their biological clock. But now that we are no longer getting up at sunrise, spending our days outdoors and going to bed when it gets dark, our body clocks get disrupted. And this can cause serious troubles. Research has linked disturbed internal clocks to anything from an increased chance at injuries and accidents to chronic health problems like obesity, heart disease and cognitive decline.