“It used to clean in the middle of the night while I was sleeping.”
Most likely the time on the clock is incorrect.
Power outages from time to time will cause the clock to get out of whack. If the timer on your softener (or iron/sulphur filter) does not have battery backup, it will either loose its clock setting and flash constantly or it will come back on at the time it was when the power went out.
Reset the clock to the proper time and everything should be fine.
Most systems have been set to start regenerating at either 1am or 2am. This is because we want them to clean when no water is being used.