My right hand does it on occasion as well...never the left. Riding (when cruising) with the old method I've always used...two fingers covering the front brake lever...forces your grip to loosen a bit. That might help some. Judicious use of the cruise control will work for sure, allowing you to "shake it out". I've never had Apes on a bike, but did have "buckhorns", or pullbacks, on an old Panhead one time long ago and far away, which made my hands higher than my shoulders, and my hands would go numb more easily. And that was when I was in my early 20's, not 60. IMO, ideally, your hands should be at or near the same level as your uppper arm/shoulder to allow good circulation, and not locked straight out at the elbow, as CVOgirl said. Too low or too high makes for bad circulation when riding.