Turns out that every living thing – men, women, animals, plants, insects, and algae – all have internal “body clocks” determined by a variety of biological rhythms. So why do we have these clocks, and what do they do for us? Here are 5 facts that may surprise you.
Subscribe http://bit.ly/1AWgeM7
Twitter https://twitter.com/HowStuffWorks
Facebook https://www.facebook.com/HowStuffWorks
Google+ https://plus.google.com/+howstuffworks
Website http://www.howstuffworks.com
Watch More https://www.youtube.com/HowStuffWorks
Music:
Jahzzar – “Meantime”
Image:
http://www.scifun.ed.ac.uk/pages/exhibits/ex-body-clocks.html
[ Circadian Rhythms Chart @ 2:24 ]
Transcript:
Your body has a “Master Clock.” There are many clocks operating within your body at the same time, distributed all throughout your cells, but they are all controlled and synchronized by a single “master clock” inside the brain. This master clock is a group of about 20,000 neurons called the suprachiasmatic nucleus, or SCN, which lives inside the hypothalamus – sort of in the center of your head, right above the optic nerve. And this organ is important. If you suffer damage to your SCN, it can cause all kinds of problems for your natural circadian rhythms, such as the timing of sleep and wake.
Internal clocks go WAY back. When did organisms on Earth first evolve internal clocks like circadian rhythms? Many scientists think that biological clocks first showed up more than 3 billion years ago to track the day-night cycle in an organism called cyanobacteria – a single-celled, ocean-dwelling creature that still exists today: We know it as blue-green algae. But why would some bits of floating ocean slime need to know the time of day? It’s not like they have to get up and go to work. This actually isn’t a totally settled question. One interesting hypothesis is that cyanobacteria evolved circadian rhythms to create time for two separate energy-production jobs – photosynthesis and nitrogen fixation – that would interfere with one another if they happened simultaneously. So we got photosynthesis during the day, and nitrogen fixation at night.
The post-lunch sag is normal. You know around 2 p.m., when you’ve just had a nice fried ice cream calzone for lunch and you’re trying to get through these spreadsheets, and suddenly you just hit a Great Wall of Sleepiness? You are not alone. In fact, the early afternoon napping urge is extremely common. Circadian rhythms don’t always fit our work schedules. Because of another internal clock known as sleep/wake homeostasis — which is basically just your body’s way of saying, “OK, I realize you’ve been awake for a while now,” — it’s normal for an adult human to feel a little drowsy after being awake for 7 or 8 hours. In fact, according to the National Sleep Foundation, the most common times for drowsiness in adults are between 2 and 4 in the morning, and between 1 and 3 in the afternoon.
Electronic light can mess with your body clock. Our natural circadian rhythms operate on a roughly 24-hour cycle, but they’re not above being corrected, and are highly influenced by our surroundings – especially light and dark. Simply put, our bodies want to wake up when the sun’s up and go to sleep when it’s dark. But in electrified societies, light and dark are not quite so predictable. Artificial lights, whether that’s the lamp in the living room or the tablet screen in front of your eyes in bed, can trick our internal rhythms into thinking it’s time to be wide awake.
Your body clock can adapt to new time zones; but not new time. If you ever want to become acutely aware of the importance of your own body clocks, just try traveling to a far-off longitude and doing everything you would normally do at the local time of day. Not so easy, huh? This effect, commonly known as jet lag, happens when your circadian rhythms are not correctly synchronized with your new time zone. Your brain is trained to release the melatonin – a hormone which induces sleep – at the wrong time of day. It can be a traveler’s nightmare – for a day or two. Fortunately, the body can usually adapt just fine to the new time zone after a little bit of practice, and a few cycles of light and darkness to re-time the melatonin release schedule. On the other hand, the body might not adapt nearly as well to Daylight Saving Time, since no one ever bothers to let the sun and the Earth know that we’ve moved 7 a.m. ahead an hour.
