I slept on a magnetic mattress for many years, believing all the hype from companies that sold them that they where good for your health.
However my legs started to suffer, weakened muscles, strain or torn ligaments and muscles.
Here is an experiment you can try. Sleep on the magnetic mattress over a few day's. Take your blood pressure, probrably it will read high. Then stop sleeping on the magnetic mattress and go back to a normal (Un-magnetized) one.
After a couple of day's take your blood pressure and you will find it much lower, normal and so healthier.