Jua let the thoughts run through your head; don't follow them up or examine them. Especially don't obsess. Let them in and let them out.

Sort of a sleep meditation.

This works well & quickly when I can do it. I haven't been too lucky lately, and the more I'm sleep-deprived the crazier I get.

Robert A Wilson recommends that when a useless and unwelcome thought comes into your head you recite the mantra "Shut the fuck up!" It works pretty good if you can remember to do it.

clint