Posts tagged ‘eyes’

Nigerian Visa Doesn’t List Blonde Hair Color Option

By Chad Upton | Editor

If you have blonde hair and you’re planning a trip to Nigeria, you may want to visit your colorist first. The online visa application doesn’t have “blonde” as an option for hair color.

nigerian_visa_no_blonde

No research turned up any answers, although I have sent an inquiry and will report back with any findings. (more…)

March 12, 2013 at 2:00 am 2 comments

A Third Type of Cell In Your Retina Regulates Circadian Rhythm

By Chad Upton | Editor

You probably learned about rods and cones in high school biology class. These retinal cells allow our brains to process light so we can see. But, there is a third type of cell that most people don’t know about: photosensitive ganglion cells.

They don’t have a cool name like Rods and Cones, but what they lack in name they make up for in swagger. Much like rods and cones, they send light information to the brain. Instead of using this information to “see”, the brain uses it to synchronize your body’s circadian rhythm to the 24-hour light/dark cycle of this planet. These “lion” cells are the original atomic clock.

They’re also used to control the pupillary light reflex. When you doctor, or local police officer, shines a bright light in your eyes, these cells are used to close your irises to limit the bright light hitting your retinas. Additionally, they help regulate melatonin — the hormone that controls several biological functions, including sleep.

Most research indicates that the ganglion cells are sensitive to light in the spectrum between 460 and 484 nm, or “blue” light which is prevalent in the visible spectrum of sunlight. Basically, this is why you get sleepy when it gets dark and why you start to “wake up” when it gets light outside.

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Photo: bigbluemeanie (cc)

Sources: nature.com, wikipedia (pupillary light reflex, photoreceptor cell, photosensitive ganglion cells, melatonin)

December 2, 2011 at 2:00 am 2 comments

Babies Blink Less Than Adults

By Kaye Nemec

I was rocking my son, trying to get him to sleep, staring at his wide-eyes as he stared back at me. I noticed that he rarely blinked and each time I blinked, I wondered if we had done it at the same time and I just missed him doing it. But, that type of coincidence can’t possibly happen every time I blink for 20 minutes, so I did some research.

It turns out, babies blink much less often than adults. Studies have found that babies, on average, blink less than twice per minute while adults blink, on average, 10 to 15 times per minute.

There are a couple of theories about why babies blink less than adults. One theory is that, because babies’ eyes are so much smaller, there is a much smaller opening through which things like dust, dirt and debris can pass. If fewer foreign particles enter the eye, less blinking and tears are needed to wash it away.

Another suggests that the more sleep a person gets, the less blinking is required. Since babies may have their eyes shut for as much as 15 hours per day, they are not as prone to dry eyes as adults, who often get 6 to 8 hours of sleep per day. When eyes are dry, blinking moisturizes them, so if babies don’t have dry eyes, there is no need to blink as often.

It is also interesting that babies do not produce tears until around the age of one month, when their tear ducts have developed. Even after that one month milestone, babies may continue to cry without tears for awhile. During the first few months, babies tend to save their tears for times when they are especially adamant about what they want or when they are in pain. So, if the purpose of blinking is to clear the eye of debris and lubricate it with tears, there is really no need for a baby to blink until they begin producing that cleansing agent.

Broken Secrets

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Sources: New York Times, The Register, Parenting

Photo: bbaunach (cc)

November 17, 2010 at 1:00 am 3 comments


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