I keep my eyes closed the whole time and do visualization like someone else said. I visualize sunning myself at the beach (to feel warm) and I picture watching hunky construction workers building me a dream beach house (to take care of the sounds that come through the ear plugs). That helps me to forget that my head is locked in that halo thing and I have even drifted off to sleep. This is from someone who is so claustrophobic that I have actually freaked out getting my head through a tight turtleneck.

I also make sure I have enough blankets to keep me warm.