Why would a publisher want to avoid night clicks? The only reason I can think of is based on the assumption that night surfers are less likely to convert than day surfers
We track conversions based on the time of day and night visitors are a horrendous waste of money for us.
While one can certainly make assumptions, I have no solid idea as to the psychological reasons behind it. I do however have two years of stats that have shown it's simply not worth advertising at night for us.