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Your bed may be killing you… July 28, 2010

Posted by mareserinitatis in electromagnetics, science.
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(Note: I posted a much more complete analysis of the paper here.)

Scientific American posted a brief review of some research stating there may be a correlation between metal bed springs and incidence of certain types of cancers, such as cancer of the breast and melanoma.

The person who wrote the SciAm article obviously didn’t read the original paper very well…or even the abstract.

In the Sci Am article, it is stated early on that there have been correlative studies showing that there is a statistical relationship between incidence of cancer and proximity to transmission antennas for radio and television.

My personal interpretation of this data is that people who live in cities are more likely to get cancer than those who don’t. This could very well be a lifestyle issue because, as we all know, correlation is not causation. And transmission towers are going to be considerably more dense in urban rather than rural areas.

The article makes the point that the amount of electromagnetic energy is so small as to be nearly irrelevant.

Anyway, the claim is that the springs in a person’s bed are capable of capturing and amplifying this electromagnetic energy, just like an antenna.

Specifically:

Thus, as we sleep on our coil-spring mattresses, we are in effect sleeping on an antenna that amplifies the intensity of the broadcast FM/TV radiation. Asleep on these antennas, our bodies are exposed to the amplified electromagnetic radiation for a third of our life spans. As we slumber on a metal coil-spring mattress, a wave of electromagnetic radiation envelops our bodies so that the maximum strength of the field develops 75 centimeters above the mattress in the middle of our bodies. When sleeping on the right side, the body’s left side will thereby be exposed to field strength about twice as strong as what the right side absorbs.

The solution, obviously, is that one should get rid of their metal bed springs.

Without even running numbers, I can tell you that this makes no sense. Antennas are passive objects. Amplifiers, however, are not passive and require the input of additional power. An antenna cannot amplify a signal. In fact, most antennas, including the one in your car, require an external amplifier so that you can listen to the signal.

Unless you’ve figured out a way to plug in your bed springs, I don’t think it’s going to do much to the signal other than capture it passively. I cannot generate a field any stronger than the one it is receiving…and generally, if it’s receiving, it’s not going to be transmitting anything.

The other problem I see, from an electromagnetics perspective, is that it just isn’t the right shape to work as a good antenna. If you look at the wire mesh in a box spring, that may work as a decent receiving antenna. However, your mesh is covered with springs and metal springs are basically going to act like inductors from an electromagnetics perspective. That is, if you have a time-varying field from the mesh, as it tries to move upwards through the springs, it will induce a current in the springs. This current, however, will generate a magnetic field which will oppose the current that induces it. If anything, I would think that it would reduce the fields around a person.

Of course, the easy way to check this would be to actually use an antenna and take measurements of the ambient field as you move toward the bed. Curious, I decided to check the original article to see if that was attempted.

It turns out that the SciAm article is completely wrong. The original article abstract states:

We found that people tend to sleep for longer periods on their right side, apparently to avoid disturbance by the heartbeat. This puts the left side farther away from the field-attenuating influence of the metal springs in the mattress; thus the left side will spend, on average, more time exposed to stronger combined fields from incident and reflected waves. This hypothesis may also explain why body parts farthest away from the mattress (trunk and upper arms for men; lower limbs and hips for women) have higher melanoma rates than the sun-exposed face area. The implications of this study should promote a critical consideration of population exposure to electromagnetic fields, especially during the night.

This is completely the opposite of what the review in SciAm stated. They are saying what I just said: the bed springs will actually reduce (attenuate) the field. They also posit that the real danger comes from the left side being away from the bed and thus exposed to EM radiation.

I still don’t know that I buy the bed-spring argument. One could argue that the safest place to sleep would be in a giant Faraday cage. Frankly, the fields transmitted are pretty weak (especially with the conversion to digital). Also, if you need to put an antenna on the top of (i.e. outside) your house to get a good signal in many cases (which needs to be amplified by the electronics in your TV), the fields are obviously attenuated by your house to some extent. Are you really going to get much electromagnetic energy hitting your body? I personally am inclined to think that there may be some other physiological factor that has to do with sleeping position but not necessarily emag.

And yes, the fact that Japanese use different beds may very well affect sleeping position which may, in turn, affect left-side prevalence in certain cancers. To assume that they must sleep the same way is a bit silly. (I say this as a side sleeper, but when I sleep on the ground, such as when I’m camping, I’m far more comfortable sleeping on my back.)

Regardless, the Sci Am summary of the journal seems to be, by all appearances, completely backwards in it’s understanding of the original research…or is doing a very creative interpretation.

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Comments»

1. Fluxor - July 29, 2010

Journalists playing scientist. Almost as bad as policiticans playing scientist.

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mareserinitatis - July 30, 2010

It’s amazing how much research has gone into the effects of non-ionizing electromagnetic radiation…and yet we’re now arguing about bed springs. Geesh.

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