leave my magnetic rug on overnight - have been using it for 4-6 hours daily pre/post exercise and really want him to have it on overnight on the nights before I ride early the next morning......
I think they just say build up gradually, if you've been leaving it on for 6 hours then I say go for it. That's what I did with my magnetic stable boots. My boy now wears them for up to 14 hours.
what ever day u can be up there all day, try leaving it on all day juts to see how it is. but to be honest if hes been wearing it for that long everyday he should be used to it and should be happy enough to wear it over night.
im sure he will let u know if hes not happy!