Feed on

It’s nearly the first day of winter and the shortest day of the year – my daily fight with my alarm as it painfully disrupts me has always been an issue, but it’s even worse lately, as it’s dark when I leave for work and dark again when I come home. Even after 5+ years working the same schedule, I never seem to meet that early morning blaring with anything but some groggy-eyed grumbling and stumbling out of my bed. Clearly I’m just not a morning person, but dark mornings are even rougher. The sun is the main influence on our daily sleep and wake cycles, so it’s no wonder the limited sunlight makes me want to do nothing but hit the snooze button.

But compared to the nearly 1 in 5 Americans who works a nonstandard schedule, I have it pretty easy. Permanent overnight work, on-call duty, and rotations are the norm in some professions, and a third of these workers might be diagnosed with shift work disorder (1), experiencing chronic insomnia or sleepiness while on the job despite having time (from a biological standpoint) to sleep during their days off. According to the American Sleep Association, in addition to obvious short term effects, shift work disorder is correlated with dangerous long term effects, including increased rates of heart and gastrointestinal diseases (as high as three times the national incidence rate when compared to the general population).

Healthy sleep and wake cycles are the result of a complex process, but melatonin (2), a hormone secreted by the brain’s pineal gland, appears to play a role in stimulating them and even adjusting them. It’s no secret that for years melatonin supplements have been marketed to promote sleepiness and to treat jet lag. But results from treating shift work disorder in a similar fashion are much less clear at this time.

File:Illu pituitary pineal glands.jpg

The pineal gland resembles a pine cone (hence the name) but was once called
the “third eye.” Philosopher/mathematician René Descartes,
believing it was the connection point between intellect and the body,
called it the “principal seat of the soul.”
(from http://plato.stanford.edu/entries/pineal-gland/[3])


I reviewed several studies from the last ten years which looked at melatonin’s role in adjusting the circadian clock to treat shift work disorder, and results were quite varied. One of the biggest issues, as is often the case in psychological/sociological studies, is translating findings in a lab to real-life situations. If you’ve ever used melatonin to help tire you or to combat effects of jet lag (I’ve tried it as a sleep aid) and work alternating or nonstandard shifts, here is some interesting research to consider:

  • Sharkey and Eastman (2002[4]) controlled for variables in previous studies and to determine whether specifically timed dosing with melatonin could produce phase shifts in individuals who must adapt to the changes in sleep schedule often associated with shift work. In their placebo-controlled study, the investigators assigned 32 healthy young adults to receive either placebo or melatonin (0.5 mg or 3.0 mg), in double-blind fashion. The protocol followed a strict sleep-wake schedule in a combination of controlled and uncontrolled settings. Subjects were scheduled to sleep for 8 hours during fixed dark nighttime periods (the phase advance), before a baseline constant routine was established. Participants took either placebo or assigned melatonin dose during the first 4 days of the phase advance portion of the trial, and all participants took placebo on other study days. They spent the first simulated night shift in the laboratory, and the remaining 6 night shifts were spent at home. Analysis of results for sleepiness and mood scales, sleep logs, and core body temperature measurements indicated that melatonin did in fact produce larger phase shifts than placebo, supporting its use to adapt to nighttime work.
  • Smith et al. (2005[5]) studied the sleep-inducing effect of supplemental melatonin given in the mornings during 5 daytime sleep periods that followed simulated night shifts to determine if individuals could fall asleep more quickly and rest more soundly during the daytime after a night-shift. The 36 participants were either given melatonin or placebo, and kept detailed sleep logs throughout the study, estimating their total sleep time. Parameters such as measures of movement, brain activity, and sleep fragmentation were measured with various lab equipment and software tools.  The investigators found that the melatonin did not produce any statistically significant increase in daytime sleep quality  when compared to the placebo. They claimed however, that these results may have either been due to the fact that melatonin was given to most subjects when internal s melatonin levels were already elevated (think a sleep-hangover effect) , or due to a ceiling effect in sleep quantity (if all participants were excellent sleepers), thereby limiting melatonin’s potential true impact.
  • Bjorvatn et al. (2007[6]) conducted one of the first studies  that assessed melatonin’s effectiveness in a real-world setting, on a population of night shift workers on an oil rig whose daytime and nighttime work schedules alternated weekly. Offshore oil rig workers were randomized and treated with bright light and either melatonin or placebo.  The research team found that melatonin and bright light led to reports of a modest reduction in sleepiness and increased sleep time by about 15 minutes per day.  However results were not statistically significant and smaller than the researchers expected.  A major limitation of this team’s study is that it was only completed by 17 subjects, and such a small sample size tends to enhance variation, making a larger sample more appropriate. The field setting in this study not only restricted the study population size, but also limited controls for other potential confounding variables (gender, age, use of prescription medications, etc.).

These three studies demonstrate a serious trade-off in science:  controlled simulations vs. real-life. Yet it’s almost always  the case that controlled, in-lab effects need to be demonstrated before looking at real populations. It can be argued that each of these have just as much merit in the scientific community and to the population as a whole. These are just a few of the studies I examined, but it’s enough to show how varied the results are, and how findings can be due to a variety of factors.

Environmental light is the main controller of our innate patterns of sleep and wakefulness, and nearly 20% of the US population works a nonstandard schedule that involves adapting to a sleep pattern that conflicts with this normal rhythm. Poor sleep quality associated with such schedules compromises health, safety and quality of life. Research assessing melatonin use as a treatment for shift work disorder is a means to addressing this issue; over the past decade, many studies have attempted to evaluate its usefulness in both simulated and real-world settings.



It’s clear in looking at the blue (sleep response to light) and red (sleep response to
supplemental melatonin) curves above that although both have the ability to
influence our sleep patterns, we respond much more to light. That’s why bright light
manipulation is often helpful in preventing jet lag, timing of course dependent
on whether you’re traveling east or west.
(from http://www.ccjm.org/content/78/10/675.full [7])

A review of the recent literature describing melatonin’s effectiveness compared to placebo indicates that results vary in terms of statistical significance, but internal factors and external confounds that may have influenced their results. In short, more research needs to be done in larger populations to determine if melatonin is a potential treatment for shift work disorder. In the meantime, there are many other steps that can be taken to improve  rest quality, ensure safety, and maintain an overall high quality of life. I found this article, from the Cleveland Clinic Journal of Medicine, to have some particularly useful information and a clear explanation of what happens when our internal clock is out of sync with the sun.


  1. http://www.sleepassociation.org/index.php?p=shiftworkdisorder
  2. http://en.wikipedia.org/wiki/Melatonin
  3. http://plato.stanford.edu/entries/pineal-gland
  4. Sharkey KM & Eastman CI. Melatonin phase shifts human circadian rhythms in a placebo-controlled simulated night-work study. Am J Physiol Regulatory Integrative Comp Physiol. 2002; 282:R454-R463.
  5. Smith MR, Lee C, Crowley SJ, Fogg LF & Eastman CI. Morning melatonin has limited benefit as a soporific for daytime sleep after night work. Chronobiol Int.2005;22(5):873-888.
  6. Bjorvatn B, Stangenes K, Oyane E et al. Randomized placebo-controlled field study of the effects of bright light and melatonin in adaptation to night work. Scand J Work Environ Health. 2007;33(3):204-215.
  7. http://www.ccjm.org/content/78/10/675.full



I just wanted to thank you all for your comments and interest in this blog.  I am very humbled and encouraged by the positive responses that I have received.  I apologize for the lack of response in the last few days – between finals and the push to get as many experiments done before the holidays, I  have been swamped.  I should have some time over this weekend to address questions, answer topic requests, and fix the typos my sister (the English teacher) pointed out to me

I also wanted to announce that Everyday Science now has a second contributor.  She is currently working on a new bio page and I am looking forward to her posts!

Thanks again!

Laura D.

Modern life involves a lot of cool electronic gadgets – cell phones, computers, tablets, mp3 players, e-readers, gaming consoles.  You name it, there is probably an electronic version available. I am guilty of being a bit of a tech junkie and when I stop to think about all the electronics I have owned over the last decade or so…  well, it’s a lot. While I was completely thrilled when i got my first mp3 player for Christmas 2004, time and technology marches ever forward and lets just say that my sleek iPod touch was a welcome upgrade.

A truncated evolution of Apple products (Photo by edtechie99)

If you’re like me, your old electronics are collecting dust in the far recesses of your bedroom closet, but you might have sold , donated, or re-gifted things that were in working order. Of course, eventually the time will come when it will break or be so outdated that it is no longer useful. Even if you are a pack rat like me, it might be hard to justify keeping something around that you haven’t used in 6 years (I’m looking at you Creative Zen).

So now what?  The temptation is probably just to throw it in the trash.  Until recently I wouldn’t have thought to do anything else with it and I fully admit having just that with an old cell phone even after I knew better.  Unfortunately, there are a lot of nasty things that go into making the electronics that we have largely come to rely on in our daily lives.  What are these nasty things you may ask? Well here is a short list just to give you a taste:

  • flame retardants
  • arsenic
  • mercury
  • lead
  • cadmium

When electronics are improperly disposed of in municipal landfills these many contaminants can leach out and contaminate the environment.  The best option is to take these items to hazardous or electronic waste disposal sites.  While these were difficult to find (or perhaps non-existant) not so long ago, many areas in the US now have municipal electronic waste disposal sites. The companies that run them may dismantle unwanted electronics, reclaiming and recycling what they can and disposing of the remaining waste in a safe, responsible manner.  Some recyclers may even refurbish items that are old, but in good working order.

Of course this is the best case scenario…

Proper handling and disposal of the hazardous materials in the US is expensive. Not surprisingly, there are some e-waste recyclers who are more concerned about increasing profit margins than following government mandated health and safety regulations.  Luckily for these “mavericks” many developing nations (often in Asia and Africa) have a large number of poverty stricken people who are willing to the work for a fraction of the cost.

Guiyu, China receives a large portion of the world’s e-waste (Photo by Bert van Dijk)

Young e-waste workers at a shop in Delhi, India (Photo by Greenpeace India)

If low labor costs weren’t enough, these regions have few, if any, regulations in place to protect the health of the residents and surrounding environment.  Circuit boards are burned in open pits or bathed in acid to recover small amounts of precious metals. Old CRT monitors are smashed apart with hammers, releasing several pounds of lead. People living in or near these communities are continuously exposed to a wide range of toxins and blood samples have been found to contain dangerous levels of lead and dioxins.  Even if the recycling practices were changed today, these areas are so polluted the environment in these regions may never recover.

Unfortunately, there is no simple solution, but there are organizations that are working to prevent the export of e-waste and ensure that it is handled properly within the US.  Below are some links to these groups:

Electronics Take Back Coalition: Recycle It Right

E-Stewards.org – a non-profit organization that helps to educate the public about e-waste issues and certifies e-waste recyclers in the US that use responsible practices.

Other resources:

The Electronics Wasteland – An outstanding 60 Minutes report on the e-waste problem in China

China’s Electronic Waste Village – series of stunning photos showing the working conditions and environmental devestation in Guiyu, China

Hrm… what should I eat? (Photo by meaganmakes)

Confessions of a Canned Food User

I, like many people, am a consumer of canned foods.  Particularly things like beans, diced tomatoes, soups, and tuna.  I love them because they save a lot of time and/or money and can live in the back of my cupboard for a long time. Unfortunately, eating a lot of canned foods may not be good for your health.  Sure they’re high in sodium and the canning process can decrease the nutritional value, but for me, the real culprit is bisphenol A (perhaps more commonly known by the acronym, BPA).

What is BPA and why should I care?

BPA is a single molecule that is combined into long chains to make plastic.  During this process, however, not all of the BPA is bound into the plastic and can get into whatever the plastic contacts, like food and beverages.

BPA can mimic estrogen in the body and cause hormonal imbalances in both men and women. Maintaining the correct estrogen levels critical and even small deviation can have negative consequences.  Exposure to BPA has been associated with increased risk for cancer, obesity and heart disease in humans and has been found to change the way the brain develops in animals.

Why canned foods?

They’re metal not plastic! Yes … But there is a plastic lining on the interior of most canned foods and drinks that contains BPA.  This lining is added to prevent corrosion of the metal, which can cause the contents to spoil.  While I understand the virtues of keeping the canned foods botulism-free, I would argue that contaminating food with toxic chemicals is not be the best way to protect public health.

The levels of BPA measured in a limited survey of canned foods and drinks were found to vary widely.  Soups and certain vegetables, like tomatoes, are believed to be the worst culprits. A recent study by researchers at Harvard University found that participants who consumed 12 oz of canned soup for 5 days had over 10x more BPA in their urine than controls eating the same amount of soup made from fresh ingredients.

Although canned drinks, like juices and soda, have much lower levels of BPA, people who consume a lot of these items (especially young children) may be at risk.

The secret ingredient? BPA!! (Photo by stevendepolo)

What about products labeled BPA-free?

In an ideal world we could figure out a way to line the can with something that does not leach chemicals into our food, but unfortunately we aren’t there yet.  Some canned food manufacturers have announced plans to switch to liners that do not contain BPA.  This may seem like a victory, but don’t break out the champagne yet…

The replacements are likely made of bisphenol S (or BPS).  I bet you’re thinking “Hey that sounds a lot like BPA!” and you are absolutely correct.  BPS is in the same family of chemicals, it also can get into our food, and it is also found to mimic estrogen in the body.  Other possible BPA replacements contain phthalates (pronounced THAL-ates) or polyvinyl chloride (PVC), both of which are known toxins.

If you are concerned about BPA (or any of its cousins) in your food the best thing to do is to stop eating them.  Period.  If you’re like me and can’t get rid of canned foods completely, simply reducing your consumption is a great step in the right direction.

This past weekend I was in Lancaster, PA for a wedding.  I stayed at a wonderful little B&B a few miles out of the city and, while sitting at breakfast with the handful of other guests and the owners, the inevitable  question “What do you do?” was asked. I explained my research as briefly as possible thinking the conversation would quickly move on to another topic.

Much to my surprise, they all wanted to know more.  I think what  and were shocked that they had never heard about flame retardants.  Although there has been a fair amount of media coverage about flame retardants recently, I am constantly frustrated by the lack of public awareness and I hope this post can help fix that.

Flame retardants are chemicals that are added to a huge number of materials, including the foam padding used in upholstered furniture and carpet padding, electronics, textiles, and some baby products to increase fire safety.  Over time they are released from the treated materials and have been found to accumulate in the environment.

1. Environmental Effects

PBDEs, a widely used flame retardant, have been measured in Arctic wildlife

Several flame retardants were recently added to the Stockholm Convention’s list of Persistent Organic Pollutants. This is an international treaty to eliminate or severely restrict the use of chemicals that meet the following criteria:

  • Resistant to degradation– once these chemicals are released into the environment, they will stick around for years, even decades
  • Undergo long range transport – Even though flame retardants are most heavily used in developed countries , they are found all over the world.  Even in places where they were never used – like the polar regions.
  • Bioaccumulate (concentrate in plant and animal tissues) and biomagnify (concentrate through the food chain, so levels are highest in top level predators, like humans)
  • Likely to adversely affect human health

Some of these chemicals are no longer being used, but it is unclear whether their replacements will be any better.

2. Human toxicity

An overwhelming number of studies using cellular and animal models have indicate that flame retardants are toxic.  These chemicals have been detected in human tissues, including blood and breast milk.  PBDEs are believed to interfere with the thyroid system, which is important for brain development, growth, and reproductive function.  Exposure to PBDEs are also associated with decreased IQ and delayed motor skills in young children.  Although some of the PBDEs have already been phased out, what is already present in the environment will be there for decades.  In the meantime, they are being replaced by other chemicals we know even less about.  One of the primary PBDE replacements in furniture is an organophosphate, a class of chemicals that includes nerve gases and pesticides.  Several organophosphate flame retardants are suspected carcinogens and may also negatively affect the way the brain develops.

3. They just aren’t effective

Flame retardant manufacturers insist that their products save lives by reducing the severity of fires and increasing escape time for those who might be trapped in a burning building, often pointing statistics showing that fire deaths have decreased dramatically since flammability standards were adopted as evidence to support their claims.  Importantly, the use of flame retardants isn’t the only thing that has changed since the 1970s.  Many other factors have likely contributed to this trend: declining smoking rates, improved building codes, and widespread use of smoke detectors in homes.

Despite what the chemical companies would like you to think, it is possible to have fire safety without their products.

The current flammability standards for upholstered furniture focus on the foam used in the cushions, but not the fabric covering.  Tests performed in 2009 by the Consumer Product Safety Commission (CPSC) compared the flame retardant capabilities of several chairs when exposed to a to a small flame.  The picture below shows a chair with untreated foam (left) and another containing flame retardant chemicals (right) four minutes after ignition.

The current furniture flammability standard only requires the foam to be fire resistant and does not account for effects of the fabric upholstery.

That’s right.  Both are engulfed in flames.  Once the fabric caught on fire, the flame retardants in the foam were ineffective.

In the same study, two other chairs were tested; again one had foam containing flame retardants while the other had no chemicals, however, these chairs also had a layer of material between the fabric and the foam that acted as a barrier. Again the picture was taken 4 minutes after exposure to flame.

Another set of chairs, this time a layer of barrier material was placed between the fabric and the foam

Little bit of a difference, no?

Again, both chairs look the same (minus the fiery maelstrom, of course). The authors of the study conclude:

“Overall, the results demonstrated that the addition of a fire barrier markedly increased the
fire safety of the furniture. …the fire-retardant foams did not offer a practically significantly greater level of open-flame safety than did the untreated foams (p. 23).”

There you have it. The flame retardant chemicals in the foam aren’t doing anything. More importantly, we can actually improve fire safety by getting rid of the toxic chemicals and replacing them with barrier materials.

4. If there is a fire, flame retardants do more harm than good

A common misconception is that burns pose the greatest danger during a fire when, in fact, smoke inhalation is primary cause of death.  Smoke created by house fires contains particles that can irritate lungs and contains deadly gases, including carbon monoxine and hydrogen cyande

“The most common, carbon monoxide (CO), can be deadly, even in small quantities, as it replaced oxygen in the bloodstream. Hydrogen cyanide results from the burning of plastics, such as PVC pipe, and interferes with cellular respiration.”

A study published in 2000 by the Journal of Fire Sciences compared the flame retardant characteristics of a number of different foams treated with chemical flame retardants.  Although these chemicals resulted in a very modest delay in ignition time (16 seconds for untreated foam vs 18-19 seconds for foams treated with a PBDE or its Organophosphate replacement, they dramatically increased the amount of soot and carbon monoxide present in the smoke.

Comparison of the levels of carbon monoxide and soot produced by different furniture foams (From Jayakody et al. (2000). J of Fire Sciences. Available at http://jfs.sagepub.com/content/18/6/430)

A more recent study presented at the 2012 American Chemical Society meeting found that, in addition to carbon monoxide, flame retardants increase the release of hydrogen cyanide.