The body (in actual fact the liver) can metabolize only a certain amount of alcohol per hour. No matter how much or how fast alcohol is consumes, the body can only dispose of it at a rate that is generally accepted as being 1 standard drink per hour. Allowing for individual variations in weight, percent body water, percent body fat, and food intake, the amount of alcohol from one standard drink will peak, in the blood stream, within 30 to 45 minutes.
The rapid consumption of four or five drinks in one or two hours overwhelms the liver with much more alcohol than it can handle. As a result BAC rapidly increases and continues to do so until drinking is stopped or decreased to a rate of less than one drink per hour. Excessively rapid drinking as will invariably lead to dangerously high BAC levels.
Someone with a BAC of .16, or twice the legal driving limit will require over 10 hours to be completely sober and after 5 hours may still not be under the legal driving limit.
Many late night revelers never think about the time it takes to sober up. Driving or performing safety sensitive duties the morning after can put anyone at risk. If an individual’s breath alcohol content is .20 after an evening of heavy drinking at 1:00 AM, they may not be under the legal driving limit of .08 BAC until approximately 9:00AM later that morning. Imagine how long it might take for the individual to be under the US Department of Transportation’s BAC limit of .02