I worried about our boys last year but they took it all in their stride. I think it depends on many things, your set up, personality of buns etc. We blocked the window to the boys shed with a towel and left a light on ( one of the battery ones) so they didn't notice the bright lights so much, then we took it in turns popping out to check on them and giving them a few treats. We're also lucky that our boys are quite laid back about things.