Its human behavior to have fear/greed, question arises how to deal with such behavior ?
In human life-cycle each one of us goes through up's and down's same goes the business cycle as well sometimes even for a short downfall the fear is made such that people stop believing themselves and act based on others talks since its so easy to influence when it comes to money as everyone has created an emotional attachment to it.
To deal with such situation you don't need to be emotionally attached to money as this is the factor which causes fear of losing and then people start acting without even thinking clearly.
So during slowdown cycle review your investments in stock whether how much financially the company or industry is affected if its just too much fear created for a short fall ( 10 to 15%) use this opportunity to add up more since its a good deal to grab a business with bargain this helps to keep the margin of safety as well.
Generally when there is feeling of fear in stock market , I go down to my mutual funds investments add up some unit over it since I get a bargain price
two mutual fund which I have in my portfolio
L&T Emerging Business Fund - 60 % of fund it covers small caps rest 40% mid caps
Franklin India Blue-chip Fund - 100% large caps
small caps and mid caps stock get heavily discounted when probability of fear is high among stock investors so I use this opportunity to add some unit whereas companies in large caps are the one who knows how to deal with slowdown and revive themselves.