Setting the clock ahead one hour is not usually a problem for the game, and I'm pretty sure that I've done that during testing without disastrous results. The problem comes in setting the clock back in time. At the very least, your stats and farm cycle will probably get messed up, along with any nursing mothers you have in your tribe. At the worst, it could kill every villager in your game.

I usually leave my computers off during the time changes for pragmatic reasons. Having spent my entire career consulting in large mainframe data center environments, I know that time-change weekends are a big deal when it comes to computers and more complex than most people realize.