What is Circadian Rhythm? - Definition & Explanation

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  • 0:01 Your Inner Clock
  • 1:43 Interruptions to Your…
  • 2:39 Consequences of…
  • 3:16 Lesson Summary
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Lesson Transcript
Instructor: Sarah Collins
Learn about your circadian rhythm, which is your body's own internal clock that tells you when to wake and when to sleep. Learn about what it manages and what can influence it.

Your Inner Clock

You've just won your favorite game show and the host is about to hand you a large bag overflowing with money. Finally, you will be able to replace that rusted-out thing on wheels and take off to Hawaii! You reach out for the prize and BEEP BEEP BEEP BEEP - it's your alarm! You awake from your dream, only to realize that you have already hit snooze several times, and now it's really time to get going. Goodbye, Hawaii. The alarm clock: a necessary evil. After all, we have to have alarm clocks or we would sleep forever, right? No, of course not. Anyone who has been able to go the weekend without setting an alarm knows that you eventually wake up unaided. Why is this?

Your body has an internal system to help it move from wakefulness to sleep and back to wakefulness. It's your own biological clock called your circadian rhythm. Coming from two Latin words: circa, meaning 'approximately' and dies, meaning 'day,' this clock regulates your sleeping pattern over the course of a 24-hour day. The circadian rhythm is mostly comprised of a group of cells called the suprachiasmatic nucleus (SCN), which is located in the hypothalamus.

It turns out that we all have a built in 24-hour day inside of you. Around 9:00pm, the body starts secreting meletonin, a hormone that helps regulate sleep. The body stops secreting this hormone at around 7:30am as your body prepares to wake. After 7:30am, levels of hormones, such as testosterone, rise to help you become alert and active. If you could allow this rhythm to fully dictate your sleep and wakefulness, you would be well rested throughout your day.

Interruptions to Your Circadian Rhythm

Circadian rhythms run on auto without any direction from you. However, there are things that can interrupt your rhythm, such as your desire to catch the 1:00 am performance of your favorite band, being awoken by your neighbor's annoying barking dog, or having to get up early for work.

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