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Shortness of Dark

Article #135 • Written by Alan Bellows

Depending on who you ask, the first practical light bulb was invented by Joseph Wilson Swan of Britain in 1878, or Thomas Alva Edison of the U.S. in 1879. Edison is the official patent holder, though a debate on the subject will often put an Edison-supporting Yank on the business end of an Encyclopedia Britannica, volume "S." Of course the debate is moot considering that the honor really belongs to Heinrich Göbel of Germany, who built functional bulbs two and a half decades earlier in 1854.

Regardless of who deserves the most credit in its invention, before the incandescent bulb began to proliferate in the early twentieth century, human sleep schedules were largely governed by the Earth's day and night cycle. But once humans possessed the technology to ward off an appreciable chunk of nighttime, we soon extended our usable waking hours by an average of 13%. Some researchers believe that this modern convenience, credited with bringing the human race in from the dark, may also be responsible for numerous ills.

The root of the problem seems to be that unnatural light spawns unnatural behavior. Life on Earth evolved for millions of years in an environment with regular periods of daylight and darkness, and long ago set its clock to this 24-hour period. The planet's earliest organisms are thought to have adapted to replicate their DNA during the night to avoid the mutations caused by daytime's ultraviolet radiation; and later, as more complex organisms appeared, more complex motives for day and night behavior appeared. Since the length of days and night are predictable, organisms have evolved to take the maximum advantage from each. This physiological cycle is known as a circadian rhythm.

In mammals such as ourselves, these rhythms are governed by a group of brain cells located in the hypothalamus. Special light receptors found in the retina gather information on the length of the day and night, and pass the data on to the pineal gland in the brain, which then secretes the hormone melatonin during what it perceives to be nighttime. This system is slow to respond to change, which is what causes jet lag in travelers.

Once humans began to use artificial light to vary the length of the day, the average night's sleep decreased from about nine hours to about seven, and the amount of sleep began to vary considerably from one night to the next. This irregularity prevents one's circadian rhythm from settling into a pattern, and creates a state of perpetual semi-jet-lag. Our bodies' rhythms attempt to appropriately adjust our alertness, blood pressure, and such for particular times of day; but we often do things contrary to this cycle, and therein lies the problem.

A growing number of doctors believe that betraying our internal clocks is the source of a host of health problems. Once night falls, the body stays awake by activating the stress response, which in turn weakens the immune system. This is evidenced by the fact that individuals working graveyard shifts are more susceptible to stress, constipation, stomach ulcers, depression, and heart disease.

There is also considerable evidence to indicate that insufficient melatonin is linked to tumor formation, including childhood leukemia and breast cancer. One study found that melatonin slowed tumor growth by up to 70% in lab mice infected with human breast cancer cells, but when the mice were subjected to constant light, cancer growth accelerated. Interestingly, blind women have been found to be less at risk of breast cancer than sighted women, lending further evidence to the notion that melatonin plays a part in cancer reduction.

The evidence that artificial light strips us of some of our well-being is not conclusive, but it is concerning. If you must stay awake during the night, it may be prudent to leave the lights out, and allow the pineal gland to do its work. So far, studies on the effectiveness of artificially-administered melatonin have shown mixed results. In any case, a regular dose of darkness may be the best preventative measure against becoming a stressed-out, constipated, ulcer-riddled cancer patient.

Article written by Alan Bellows, published on 13 March 2006. Alan is the founder/designer/head writer/managing editor of Damn Interesting.

Article design by Alan Bellows.
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34 Comments
rafnex
Posted 13 March 2006 at 05:59 pm

jeez that'll mean no more overtime for me :D


klone
Posted 13 March 2006 at 06:57 pm

i have been reading a book called "Four Arguments for the elimination of television", it has a large section on how unnatural light affects humans. very interesting.


Pascal Leduc
Posted 13 March 2006 at 07:35 pm

Bah its not the lights fault, its how we use it. plenty of people sleep a full 8 hours and more despite having access to lighting, and irregular sleeping schedules are for the foolish. Plus, what about those who live in polar contries are you telling me that the fact that im still awake at 5 is unnatural?


wileybot
Posted 13 March 2006 at 07:52 pm

This topic has been "digged"...hang on!


Tynan
Posted 13 March 2006 at 08:45 pm

I'll never forget how incredibly well I slept after a few weeks in the wilderness with no artificial light except from a campfire. Judging by the contrast between that and my ordinary half-insomniac status I'd say there is definitely some truth to this story.


Iscariot
Posted 13 March 2006 at 08:59 pm

Yet another reminder for me to wake and sleep at reasonable times. I should really get on that.


Anonymous User
Posted 13 March 2006 at 09:05 pm

Man will evolve and adapt.


Anonymous User
Posted 13 March 2006 at 10:06 pm

"A growing number of doctors believe that betraying our internal clocks is the source of a host of health problems."

If you're going to claim that doctors believe it, then cite some articles in reputable journals. I'm sure that Science or the New England Journal of Medicine would jump at publishing articles that conclusively linked artificial light to various maladies.

I think that you'll find the problem is that there aren't any such studies. Reading it on 'teh Intarwebs' does not make it so.


God of Biscuits
Posted 13 March 2006 at 11:01 pm

I didn't actually read the article you're all talking about, but I'll offer my opinion anyway. Your comments remind me of how I drove my pickup down to Florida on I-92 South, dag gone, shootin' possom on the way. I tell you what, them dag gone possom come outta the swamp, dag gone drunk as H-E-double hockey sticks. Boy, I tell you what.


Alan Bellows
Posted 13 March 2006 at 11:49 pm

Anonymous User said: "I think that you'll find the problem is that there aren't any such studies. Reading it on 'teh Intarwebs' does not make it so."

See the National Institutes of Health link in the article above.


angrycrying
Posted 13 March 2006 at 11:59 pm

Scholar.google.com is also a good source for further articles that suggest melatonin can help ward off cancer formation - for instance, search for for "dna replication melatonin":

Melatonin as a Chronobiotic / Anticancer Agent

Melatonin inhibits proliferation and melanogenesis in rodent melanoma cells

Antioxidative Effects of Melatonin in Protection Against Cellular Damage Caused by Ionizing Radiation

The first link is a review of the topic with lots of detailed information - if you view the full 20-page PDF, it cites 91 other articles as sources.


fred
Posted 14 March 2006 at 12:10 am

Well I am shocked. Yet another stupid pseudo-scientific article on the internet.


Ricky JJ
Posted 14 March 2006 at 03:45 am

Shocking indeed!

Very interesting though

---
http://www.wirah.com


bigtech
Posted 14 March 2006 at 07:58 am

Wow, so that must mean that people must be dying younger since the advent of the lightbulb!


cosmos
Posted 14 March 2006 at 08:36 am

I'm surprised that there is no mention of light's effects on the female cycle. Women's menstrual cycles are typically 28 days long - same as a lunar cycle. The article stresses the potential problems with artificial light and the importance of darkness, but it neglects to mention the big, glowing orb that lights up the night sky, extending our usable waking hours. Under "natural" conditions, women will ovulate with the full moon and menstruate when the moon is dark. There are many well documented animal studies supporting this.

Personally, I find that I simply sleep better in total darkness. Women who wish to normalize their menses and improve fertility can try sleeping in total darkness for most of the month, and sleep with a night light on days 14-17.


rp2
Posted 14 March 2006 at 09:36 am

Oh my god I freaking hate you Alan Bellows. How could you write this article. I have only heard this same article over and over like a million times divided by zero. I think its neat-o.


orc_jr
Posted 14 March 2006 at 10:08 am

i found me a dead possum in a hole full of rainwater once.. i used me a long stick to poke it into a bucket tied to a rope so i could pull it out 'n there were like 8 dead baby possum come a'floatin' out that ther' pouch. them's was some good eatin's!


Anonymous User
Posted 14 March 2006 at 10:14 am

fred said: "Well I am shocked. Yet another stupid pseudo-scientific article on the internet."

Well I am shocked. Yet another moron who lacks reading comprehension skills.


rhea_sun
Posted 14 March 2006 at 11:40 am

Seems interesting that the US has decided to again mangle with day-light savings time once again. After reading this article it seems as it may do more harm then good.

bigtech said: "Wow, so that must mean that people must be dying younger since the advent of the lightbulb!"

I imagine that the advance of science, medicine, diet and world economy have more to do with life expectancy than the amount of artifical light we get in a day, but it could explain some of the "stress, constipation, stomach ulcers, depression, and heart disease" as mentioned. Not everything on that list automatically kills, especially with so many over-the-counter items readily available.


cosmos
Posted 14 March 2006 at 12:22 pm

I have read that the increase in life expectancy has more to do with the implementation of basic sanitary measures than the "miracles" of modern medicine. Humans are actually getting sicker - look at all of the modern diseases that are on the rise despite advances in science. Cancer, heart disease, Alzheimers, Diabetes are all reaching epidemic proportions.

Skeptics - If you feel that there has not been any research on this subject, or that it is "junk science" visit PubMed (a database maintained by the National Library of Medicine and the NIH) and do a search. I turned up about 1400 published studies having to do with light, darkness, sleep and circadian rhythms!(http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed)

There are so many factors contributing to our modern ills. If sleeping in a darkened room might have some benefit, even if it just helps you to get a better night's sleep, why not try it?


rp2
Posted 14 March 2006 at 12:25 pm

because the darkness kills....................


Pascal Leduc
Posted 14 March 2006 at 12:44 pm

Humans are actually getting sicker - look at all of the modern diseases that are on the rise despite advances in science. Cancer, heart disease, Alzheimers, Diabetes are all reaching epidemic proportions.

Thats not exactly true, more people are dying of these illnesses because the more common causes of death are greathly reduced. Like the cynic will say, if you find a cure for a disease your not saving anybody, your dooming them to die from something else.


cosmos
Posted 14 March 2006 at 01:21 pm

Unfortunatly, these ARE the "common causes" of death now. How many folks do you know of that actually died of old age? Ha Ha. Even if people make it to elderhood they are most likely affected by the above diseases and not healthy. We're all going to die of something though...

rp2 - Don't be afraid of the dark! :)


rhea_sun
Posted 14 March 2006 at 02:44 pm

Dying of old age has never been the "norm." Most old folks die of pnuemonia anyways. It's always something. Perhaps we can just label the causes of death better than in the past.


another viewpoint
Posted 14 March 2006 at 08:57 pm

...well then, somebody better NOT tell all them chickens that we've been foolin' them into increasing egg production by keeping the windows closed and drapes pulled shut in the coops so the artificial sunlight can be on longer. Then again, what do you want for an animal that's got a brain the size of pea.

...if you want to live to be a ripe old age, then you better get used to waking up every morning. If you want to be sure you wake up each morning, then you better drink plenty of water before you got to bed at night.

...and with that, it's getting late and time to go look for pinholes in my eyelids.


davida
Posted 15 March 2006 at 09:07 am

I'm a good friend of Alan...he stays awake until 2am everynight...and I'm pretty sure he can't see in the dark. no doubt he is an expert on this subject...damn interesting..... damnironic....etc


Chilehead
Posted 16 March 2006 at 06:38 pm

It would be interesting to see some studies relating health and varying periods of light and dark because the length of days and nights on earth is never really a constant: The tidal effect of the moon and sun dragging the tide around the Earth from west to east have constantly been slowing the Earth's rotation. Days on Earth used to be much shorter than they are now, and in the far future (probably the order of a billion or so years) the length of our days will reach the 47 hour mark. (source: Cosmos author: Carl Sagan)


Armani
Posted 18 March 2006 at 12:36 am

your scientific journal proof is Momma said sleep on time. People that take long night shifts die faster and get paid more: what a deal? Not sleeping on a schedule is definitely unhealthy and i would agree with Cosmos that the new diseases that spawn are reaching epidemic proportions. The new "advances" do make you sicker then what you gain. For example, women that recieve annual breast check ups never think that they have to get x-rayed to see the results. X-rays = bad and is probably why women get breast cancer. "wow docter, thank god i got my annual breast exam so i know i have cancer ahead of time"


orc_jr
Posted 20 March 2006 at 01:53 pm

Armani said: "your scientific journal proof is Momma said sleep on time. People that take long night shifts die faster and get paid more: what a deal? Not sleeping on a schedule is definitely unhealthy and i would agree with Cosmos that the new diseases that spawn are reaching epidemic proportions. The new "advances" do make you sicker then what you gain. For example, women that recieve annual breast check ups never think that they have to get x-rayed to see the results. X-rays = bad and is probably why women get breast cancer. "wow docter, thank god i got my annual breast exam so i know i have cancer ahead of time""

liar! x-rays are good for you! also, you're ugly.


comforteagle
Posted 27 March 2006 at 04:15 pm

According to my homebrew sleep research (http://fooworks.com) a person should go to bed around 9:30 - 1opm in order to hit maximum sleep, maximum restorative health, and maximum cognitive ability for the next day. All oddly in line with circadian rhythms to this day.


Bianca
Posted 01 April 2006 at 05:40 pm

In response to leaving a night light on during days 14 - 17 to improve fertility, this will not give your eyes total rest. I've read it can cause vision problems, but perhaps not if short term.


Hayley
Posted 04 June 2006 at 06:48 pm

I've read that sleeping an average of 7-8 hours a night increases longevity of life by some significant amount, while more and less decrease it. I guess my mum was right when she suggested a set bedtime every night to keep my sleep regular. Unfortunately, I haven't stuck to that....


nomentanus
Posted 09 December 2006 at 08:17 pm

PhotoperiodEffect.com gathers various research to suggest that perhaps most of the "diseases of Industrialization" such as diabetes and MS, that have skyrocketed in the last two hundred years, are light exposure diseases. (Gas lighting came in two hundred years ago, and was more revolutionary than the transition from gas lighting to electric light.)

The importance of sleep (and presumably darkness) hygiene to depression and manic depression is now widely accepted as well.

PhotoperiodEffect.com traces much of this to the negative effects on mitochondria, our energy engines, of doing too much with too little time for them to repair and reproduce.


Beautiful Confusion
Posted 21 August 2007 at 08:20 am

So I guess it's a bad idea to let your kids sleep with a night light? I wonder how those people that can't sleep without the TV on do with their health? I had a friend that could not sleep without the light of the TV on and the TV was right next to her head by her bed. She was riddled with health problems, I wonder if it's connected.


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