Mad Men fans are breathlessly awaiting a reunion with their favorite dysfunctional ad executives as the acclaimed AMC drama series makes it grand return this Sunday, after an almost unbearable 17-month hiatus.

Though we won't know if Don Draper will re-emerge as a married man, or if Sterling Cooper Draper Pryce will be in the black, we can almost certainly expect cocktail hour to be alive and well on Madison Avenue -- at all hours of the day.

While Mad Men had been repeatedly criticized for promoting a glamourized and unrealistic image of functional alcoholism, in season four we saw the drinking habits of Sterling Cooper Draper Pryce cast in a more serious light.

In Waldorf Stories (episode six), the consequences of Don's excessive boozing -- previously contained to self-destructive nights and weekends -- spill into the professional sphere,  when he arrives blackout drunk to a hastily rescheduled Life cereal pitch meeting.

The next episode finds Peggy escorting Don through yet another bender, and the two encounter a raving drunk Duck Phillips back at the office. Minor mayhem ensues.

When Don asks for another drink after he's been sick, Peggy asks: How much longer are you going to go on like this?

And how much longer can Mad Men get away with will allowing Don to operate as a functional alcoholic, when his drinking habits are unassailably dysfunctional?

Matthew Weiner has been noticeably protective of revealing the calendar point when season five picks up -- which suggests there could be something significant about the timeline. He's confessed that a (presumably) important line of dialogue in the upcoming season is When is everything going to get back to normal?

For most of the (male) employees of Sterling Cooper Draper Pryce, a normal day involves a steady stream of whiskey and/or vodka. Both Don and Roger Sterling's drinking problems are arguably at a 'something's-gotta-give' crisis point -- rock bottom can't be far away for at least one, if not both. But in the Mad Men world -- where life is routinely on the rocks -- it's hard to say what, or where, the bottom is.

As Scott Meslow of the Atlantic points out, only a villain and a supporting character have faced catastrophic consequences for problem drinking:

Despite their alcohol problems, Don Draper and Roger Sterling remain half of Sterling Cooper Draper Pryce-and spend the vast majority of the series looking immaculate and functioning well. There's a pragmatic (and arguably) cynical reason for that; though the series serves many functions for viewers, one of them is a kind of lifestyle porn...That was less problematic in the series' early episodes, before the characters' alcohol problems were so apparent, but the evolution of its plot has made its veneration of cocktail culture a little queasier (a series with a lead character who's battling alcoholism should not be using that character to promote a Cocktail Culture app for the iPhone).

While Roger manages to be loveable in spite of his alcohol problem, Don may only be sympathetic because of his. His weakness for the bottle lends him a humanity and vulnerability that is difficult to locate elsewhere.  And while -- at least more recently -- his excessive imbibing has led to some particularly unflattering episodes, Don is sometimes at his most pleasantly reachable when he's drunk: A warm, unusually revealing exchange with Peggy in The Suitcase comes to mind.

Peggy's relationship with alcohol may also be something to watch. Meslow also noted that only the men on Mad Men struggle with alcohol, and season four saw Peggy scaling back her own moderate consumption -- perhaps in response to watching her co-workers and friends falling apart; perhaps to take sober advantage of potential opportunities their incompetence affords her.  Peggy has always had to find creative ways to stand out in a man's world; if she's surrounded by drunks, it follows that she would respond with temperance.

Though Weiner was tight-lipped on the details, he assured The Huffington Post that season five will be a new story. Here's hoping that could mean Don turning over a new leaf.