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Again, some toys for geeks

February 2, 2006

After the IR camera, I bought a dB meter and a light meter for the laboratory. They were the cheapest ones available (but they are still costly, around 150 euros, knowing money is coming from my own pocket).

The dB meter measures noise level. In my office, it measured 62 dB (approximately). According to the Wikipedia article on Decibel, it’s between “Office or restaurant inside” and “Busy traffic at 5 meters”. The problem is that I am exposed to this continuous environmental noise everyday, at least 8 hours a day. Now I can put a number on the reason why I appreciate silence and calm. Fortunately, I only have a few months left, here.

And, in fact, I didn’t bought it for me. I bought it to measure noise level in the room where we are keeping rats. Same number: around 66 dB. It’s high but still below the recommendation of 83 dB. And we cannot do anything to reduce this noise since it comes from the ventilation (we must keep this level of ventilation to maintain an adequate temperature, relative humidity and to renew the air).

A light meter is a device used to measure the intensity of light. It shows results in lux (a measure of the perceived intensity of light). All our activities are influenced by the amount of light we receive (cfr. Seasonal Affective Disorder, e.g.) and light is also a powerfull zeitgeber (time giver) for our circadian clocks (yes, we all have many ones!).

In my office, with only 2 neons on the ceiling and my computer screen, my eyes receive 65 lux, which is far from acceptable! When I switch on my desk lamp (a “lamp” to see radiographies, in fact), I receive 260 lux (that’s ok for an office: recommendation states between 700 and 2000 lux). Outside, just in front of the lab, there are 455 lux (it’s 16:00, cloudy, foggy (and cold!). You can imagine how much you eye should receive if it was sunny …

Once more, I didn’t bought the light meter for me but for the rats. Rats that are ready for experiments receive 406 lux and rats that just entered our animal housing unit receive 260 lux (they are placed one rack below the first ones). 400 lux can be considered as a lot of light: the average light intensity in the litterature is around 200 lux. I think I will reduce the light intensity in their room.

What’s wonderful is that some people found that the more a rat receives light, the more it will sleep. Moreover, light has an influence on body posture and wall contact. But it has no influence at all on eye closure nor cage position. So, the next time you’ll go to sleep, pay attention to the light and your own behaviour (provided there is a direct link between rats behaviour and humans one).

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