Feeling crummy more than a day after an alcohol session this Christmas should give us pause for thought.

The alcohol response of our brains changes depending on our alcohol exposure over the past few hours and days and, less obviously, that over the last few months and years.

In our student days and early twenties, for instance, many of us might drink enough to move our brains into the outer regions of dependency, where our neurons misbehave.

No klaxon accompanies this shift so we may never know it happened. And our recovery from it can happen without us knowing too, with our drinking levels falling as our circumstances change.

But we can also inch into dependency at any time if we drink heavily for long enough, perhaps triggered by friends, a trauma or Christmas. We can unwittingly inch out of dependence again too. But we can’t rely on it.

So how do we know where we stand? It is not easy. If we drink less than the UK guidelines of 14 units (140ml) of alcohol a week for months, there is little chance of a problem. If not, we can’t be so sure.

We can look for clues, however: If we binge-drink, the classic pattern of the enthusiastic “social drinker” in northern Europe and North America, then our recovery after a heavy one is a good place to look.

Overlong aftermath

Having routine hangovers means we are not looking after our brains very well and could eventually face difficulties. But discomfort within the first 24 hours is a normal reaction to an alcohol overdose.

But feeling meh more than 24 hours after an alcohol session is something else. We might think it is a “prolonged [or delayed] hangover”, but it is not an overdose rebound, but a reaction to absence.

We have, in other words, some degree of withdrawal. We might sweat, have headaches, feel grumpy, tense, forgetful or nauseous. If we have anything more than the mildest discomfort we should go and see our doctor.

“Two-dayers”, as this phenomenon is sometimes dismissed, are potentially a sign we are flirting with alcohol dependency. Nobody wants to find this out, but the sooner we do, the easier it will be to reverse.

Avoiding heavy alcohol use for three months to a year is typically enough to be rid of it. Making this change on purpose is not always easy, but we can get help from our doctors and online and offline support.

If we stick to it we can reasonably expect clearer thinking, better memory, improved and more stable mood and better sleep. And, on a more practical level, we can substantially cut costs and so improve our finances.

Looking out for “persistent hangovers” or “two-dayers” can enable to look past unhelpful folk wisdom and misinformation to identify a potential problem, a crucial step in improving our long-term wellbeing. ■