There is an old Wall Street adage that says "sell to the point of sleep". I have found that a variation of that statement works a lot better for me. Often when I cannot sleep, the market is in turmoil and it is not a good time to sell. I find that the best thing to do is to suck it up and take the pain and sell at the next opportunity.
Last week when we were crashing I felt like I was losing my mind. When we rallied back I took some positions off and added some hedges even though I was still bullish. As a result I am in much better shape today than I was last week at these levels both from an account value and sanity perspective. Don't get me wrong , I am having a painful day but not nearly as painful as it would have been if I did nothing.