The first is that there does seem to be something useful about slowing circulation when we are ill. One idea that has some data to support it is that when we slow our circulation, our blood circulation, so not running around so much or running it all, but rather lying down, getting extra rest, maybe sleeping, maybe even just remaining still, is that the lymphatic system, which carries a lot of the immune-related cells and fluids, is able to ramp up its levels of activity.