The best answer would be Time.
The best answer is time because, it takes time to get off of an addiction such as drinking. Becoming sober doesn't happen out of no where. The more time a person has to sober up the greater the chance of them overcoming there addiction of drinking.
The more time someone that has an addiction, the better they get.
Some people think addiction can become overcomed if someone simply get's sleep, or drink coffee but stuff like that doesn't work.
People that have addictions need months of therapy to sober up. Sometimes it takes years, anything can bring back drinking. So the more time they have to get over he addiction, the greater chance that they'll be better.