Not all Electro-Magnetic Fields are bad for you. In the case of PEMF, it is being used to recharge your cells. Each cell in the human body has its own small electro-magnetic field operating between 0-30Hz. The Earth also has an electromagnetic field, usually around 7.83 Hz and is referred to as the Schumann Frequency. This is the type of magnetic field our bodies have evolved to operate in but due to increasing technology we are further and further away from that frequency. The Zen bed utilizes that same Earth frequency.
If you are interested in looking at studies using PEMF technology, there are over 450 studies on pubmed. See http://www.ncbi.nlm.nih.gov/pubmed.
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