Does the negative ions function turn off after 1 hour? Is there a way to keep it on all night?

Negative Ions are always generated when any Ereada® mat is ON or even when you lay on an unpowered mat (its crystals and anion layers generate ions upon smallest heat distortion).

Negative Potential function of Brown Ereada® mats and Gemstone Mini mats with N.P. is an additional function and works in a different way.

It is similar to Richway E.D.N.I. (Electrical discharge of negative ions) when ions are generated by the special silver fiber layer inside the mat receiving DC from the controller. It works only for 1 hour on the bigger than mini mats and for half an hour on mini mats with N.P.

Air ion function of bigger than mini Purple and Gemstone mats also works for 1 hour with auto shut-off. 

But if you need to stop earlier or reactivate any of these functions you should press ION or NP button again.

Again, even when all additional functions are OFF and the mat is not heating, the mat will naturally produce negative ions using the warmth of your body.