You can do something else in the meantime, just leave OTTD running. You can be AFK for hours, as long as OTTD is running and you're still in your company.
There's only a limited amount of slots available for companies, people who go offline and stay away for a while, lose their company to make place for others. I don't even know if it's possible to have all kinds of conditions attached to the resetting, like over a certain company value or something, but I would be against it.
Most of our servers can be done in a few hours time, a little longer if you don't actually build all the time, but all but 1 can easily be done without having to go to sleep before you leave. As for other activities (and even sleeping actually) you can leave your OTTD running.
A last point, you or another company could reach the goal before you wake up again, since you're not online and in your company, you won't score points.
So, the solution is, stay online or don't leave for a longer time. As said before, if you play at location A and want to continue a little later at location B, make sure you're logged in, have a password-protected company and the time between leaving and entering again shouldn't be too long. By typing !resetinfo ingame you can find out after what time your company will be reset. Remember a year takes just over 13 minutes and calculate how long you have time to be away for.