Those offers you can’t refuse are messing with your head. Ads and store layouts purposefully trigger primeval brain centers wired for happiness and instant gratification. And remember why they call it Black Friday: it’s not about you, it’s about the stores’ bottom line. Prices will likely drop further in December. Factor in the cost of gas and the hours spent waiting and browsing, and it might make more sense for your wallet — and your brain — to sit this one out.