Autoextender Usage Question

I’ve decided to rededicate myself to my PE endeavors. Purchased an Autoextender, new silicone version from the website. I’ve now used it twice, at relatively moderate levels of stretch for 2-3 hrs each time. I’ve noticed my head gets very cold, and second time my entire unit was numb. I did use the new prewrap that he includes and again the stretch level was low-moderate pressure. If it does this in 2 hrs, I’d hate to see what 8 would do! Any suggestions? Thanks.