You wanna be careful if other people are on the server with different timezones, because of a combination of things :

• you still have sleep turned on, where you need to sleep or you are tired
• sleeping makes the in-game clock fast-forward when everyone is sleeping or no one else is on the server
• Zomboid has an internal series of events, so to speak, and as time goes by the world becomes much harder to survive in.

So you could have someone logging on after a day or two, and suddenly in-game a few weeks have gone by, the water's shut off, the electricity's gone and zombie hordes are plaguing most cities making them impossible to survive in without good gear.