I sleep better in Faraday cages, and the electromyogram data suggests one reason why: an odd waveform (screencap attached*) detectable on the skin surface that seems to correlate with sleep disturbances.
* (Taken from a night where I was using no “active countermeasures.”)
Unfortunately, Faraday cages are notoriously bulky and unsuitable for traveling. To rectify this, I’ve tried all sorts of solutions — mostly along the lines of active ‘jamming’ with pink noise. Pink noise through a low-power audio amplifier, a reversed audio output transformer, and into the skin via copper electrodes has been the most successful of these attempts. But it still was only a band-aid fix.
What about fabric shielding? Conductive fabric is widely available, courtesy the ‘maker’ movement. It’s also bloody pricey.
However, the electromyogram does allow for localizing the signals. I’ve noticed that the detected waveform amplitude is much higher on certain patches of skin than it is on others.
So I tried covering just those areas with conductive fabric. I didn’t expect much… but all of a sudden my subjectively experienced quality of sleep is very near what it is inside a big-and-bulky mesh box.
Unfortunately, this effect is nearly eliminated by putting an EMG electrode under the conductive fabric, so it’s not possible to say whether the conductive fabric has the same effect on the observed waveform that a proper Faraday cage does. (Using the EMG inside the Faraday cage, I noticed the observed waveforms were vastly weaker, and often much more ‘sparse’ — as if they’d been passed through a differentiator.)