I’ve started sleeping with Better Earthing System and I feel warmer. What is going on?

That’s your circulation improving. The research studies that have been done on earthing show that contact with the earth improves blood flow around your body. That’s because it gives an extra negative charge to the surface of your red blood cells, which in turn stops them from clumping together and becoming sticky or viscous. One byproduct of this is a feeling of warmth especially in your hands and feet, but also throughout your body.