A fan is always good,Your just mimicking the wind and the wind blows at night time too,the only reason i dont have mine on is because i have to run another lead into my tent thats not hooked up to the timer.
sorry for the random question, but is it cool if i leave my lights on 24/7 then all of a sudden have em lik 12/12 for like a while or does that shock the plant? im just afraid of the electricity bill