Is it bad to turn off the water to your home over night in the winter time?

Well, if the pipes freeze you would then have no water supply to your home.

Yes it is very bad for you to turn the water off in the house in the winter time. Why do you need to do this?

I can't think of a reason to do this unless you have something that is already laeking. It would be OK to shut down your supply under most circumstances. Your home must be properly insulated, not piping within an exterior wall and it can't as a darn cold as it is in Chicago this morning. We will be hitting 10 below this weekend and that kind of stinks. Older home may be poorly insulated and it was once common to have supply and drain lines within exterior wall caviteies. Its up to you to determine your situation based on locale and home.

That shuts the water off to the hot water tank. It is very bad to ever shut the water off to a hot water heater without opening a hot water tap unless youhave an expansion tank.