During the 12 plus hours the market was closed news can change investors opinion of the stock. (money.stackexchange.com)
On the other hand, if prices start to trend downward after the low spike, the spike may be an indication that news about the company has changed investor opinions about the stock. (investopedia.com)
I don't know about everyone, but among quantitative investors the opinion is virtually universal that trend following is the right strategy. (alephblog.com)