By Julian Joyce BBC News This year's Christmas drink-drive campaign throws the emphasis on the morning after. Knowing you are over the limit on the night is one thing, but it's far more complicated to be sure the next day.
By Julian Joyce BBC News This year's Christmas drink-drive campaign throws the emphasis on the morning after. Knowing you are over the limit on the night is one thing, but it's far more complicated to be sure the next day.
It's 8 o'clock in the morning after the night before. There's a background ache in my head, the product of too many strong lagers. My mouth is dry and there's a vague uneasiness in my stomach.
It's 8 o'clock in the morning after the night before. There's a background ache in my head, the product of too many strong lagers. My mouth is dry and there's a vague uneasiness in my stomach.
This time it's not the after-effects of yet another Christmas party, it's about trying to understand the uncertainty behind this year's anti-drink driving campaign.
This time it's not the after-effects of yet another Christmas party, it's about trying to understand the uncertainty behind this year's anti-drink driving campaign.
ABSORPTION OF ALCOHOL 20% absorbed in stomach/80% in upper small intestineMost rapid when stomach is emptyAccelerated by tolerance (habituation) to alcohol Decreased by food in stomach Other factors include emotional state, drugs, type of alcohol drunk Source: Department of Forensic Medicine, University of Dundee It warns that people getting behind a wheel the morning after a big night out - while they are still over the legal alcohol limit or unfit to drive - is a growing danger.
ABSORPTION OF ALCOHOL 20% absorbed in stomach/80% in upper small intestineMost rapid when stomach is emptyAccelerated by tolerance (habituation) to alcohol Decreased by food in stomach Other factors include emotional state, drugs, type of alcohol drunk Source: Department of Forensic Medicine, University of Dundee It warns that people getting behind a wheel the morning after a big night out - while they are still over the legal alcohol limit or unfit to drive - is a growing danger.
Statistics back up the message. One in five drivers found drink-driving are caught the morning after, according to the Department for Transport (DfT).
Statistics back up the message. One in five drivers found drink-driving are caught the morning after, according to the Department for Transport (DfT).
More than a third of us underestimate when it's safe to drive the next day and nearly half of young drivers admit driving after drinking heavily the previous evening, according to figures from the road safety charity Brake.
More than a third of us underestimate when it's safe to drive the next day and nearly half of young drivers admit driving after drinking heavily the previous evening, according to figures from the road safety charity Brake.
And there are no shortcuts. The sobering qualities of a cold shower or a cup of coffee are just a myth; they won't make you fit to drive any faster and it's dangerous to think so, say experts.
And there are no shortcuts. The sobering qualities of a cold shower or a cup of coffee are just a myth; they won't make you fit to drive any faster and it's dangerous to think so, say experts.
Time is the only thing that will to get the alcohol out of your system and the big question is how much?
Time is the only thing that will to get the alcohol out of your system and the big question is how much?
According to government guidelines it takes at least one hour for every half pint of beer, glass of wine or measure of spirits to get out your system. You should count the hours from the time you finished your last drink.
According to government guidelines it takes at least one hour for every half pint of beer, glass of wine or measure of spirits to get out your system. You should count the hours from the time you finished your last drink.
Impossible to know
Impossible to know
But it's a confusing subject. Just this week, a survey found people in their 30s and 40s are more likely than 20-somethings to say they've drunk too much. One explanation mooted by Alcohol Concern is that, with age, alcohol stays in the blood system longer.
But it's a confusing subject. Just this week, a survey found people in their 30s and 40s are more likely than 20-somethings to say they've drunk too much. One explanation mooted by Alcohol Concern is that, with age, alcohol stays in the blood system longer.
Then there's the varying glass sizes and the increased strength of alcoholic drinks. The Office for National Statistics announced last week it had revamped its assessment methods for how much alcohol we drink because of these two issues.
Then there's the varying glass sizes and the increased strength of alcoholic drinks. The Office for National Statistics announced last week it had revamped its assessment methods for how much alcohol we drink because of these two issues.
It all depends on body-size, what you have eaten and your general level of fitness Brake guidance Most obviously, we are all different shapes and sizes, with different metabolisms - no two people are the same. Because of this there can be no definitive answer about when you are safe to drive after a heavy night - it's impossible to generalise.
It all depends on body-size, what you have eaten and your general level of fitness Brake guidance Most obviously, we are all different shapes and sizes, with different metabolisms - no two people are the same. Because of this there can be no definitive answer about when you are safe to drive after a heavy night - it's impossible to generalise.
Nevertheless, it's a question we might reasonably ask ourselves. There are some qualifications needed at this point. I'm aware I should not try to apply my conclusions to the population as a whole, as campaigners point out.
Nevertheless, it's a question we might reasonably ask ourselves. There are some qualifications needed at this point. I'm aware I should not try to apply my conclusions to the population as a whole, as campaigners point out.
"Alcohol stays in the body for different lengths of time, depending on a variety of factors," says a Brake spokeswoman. "It all depends on body-size, what you have eaten and your general level of fitness."
"Alcohol stays in the body for different lengths of time, depending on a variety of factors," says a Brake spokeswoman. "It all depends on body-size, what you have eaten and your general level of fitness."
So here are the facts: I am above average build - 6ft 1in tall and in my mid 40s; I weigh 15 stone and 12 pounds and although I'm overweight I like to consider myself generally fit. I cycle about 12 miles to and from work each day and would normally describe myself as a "moderate" drinker.
So here are the facts: I am above average build - 6ft 1in tall and in my mid 40s; I weigh 15 stone and 12 pounds and although I'm overweight I like to consider myself generally fit. I cycle about 12 miles to and from work each day and would normally describe myself as a "moderate" drinker.
The experts agree I would naturally be more affected by alcohol if I were smaller, or female.
The experts agree I would naturally be more affected by alcohol if I were smaller, or female.
Well over the limit
Well over the limit
My night on the town isn't a bacchanal by many people's standards. I drank five pints of premium-strength over the course of the evening, while enjoying a two-course meal. I finished drinking at 2345 GMT.
My night on the town isn't a bacchanal by many people's standards. I drank five pints of premium-strength over the course of the evening, while enjoying a two-course meal. I finished drinking at 2345 GMT.
A home breath test gives guidance to driversI've clearly had too much to drive by the end of the evening, and I get the bus home. To prove my inebriation I test myself when I arrive back using an AlcoSense portable breathalyser.
A home breath test gives guidance to driversI've clearly had too much to drive by the end of the evening, and I get the bus home. To prove my inebriation I test myself when I arrive back using an AlcoSense portable breathalyser.
It's specifically marketed at motorists who want to make sure they are sober enough to drive in the morning. The device looks not unlike a mobile phone with a tube attached. You blow into it and it tells you whether you are under, borderline or over the drink-drive limit.
It's specifically marketed at motorists who want to make sure they are sober enough to drive in the morning. The device looks not unlike a mobile phone with a tube attached. You blow into it and it tells you whether you are under, borderline or over the drink-drive limit.
When I get home at 0100 and blow into the device the screen predictably flashes red and beeps loudly. My blood alcohol concentration (BAC) reads 0.11%, well over the legal limit of 0.08%. This is probably near the peak of my alcohol absorption, according to experts.
When I get home at 0100 and blow into the device the screen predictably flashes red and beeps loudly. My blood alcohol concentration (BAC) reads 0.11%, well over the legal limit of 0.08%. This is probably near the peak of my alcohol absorption, according to experts.
At 0700 the following morning I get up and test myself again using the same device. The reading is clear - if the machine is to be believed, over the course of the night the alcohol has dissipated from my system.
At 0700 the following morning I get up and test myself again using the same device. The reading is clear - if the machine is to be believed, over the course of the night the alcohol has dissipated from my system.
To make sure my results are genuine, I'd previously arranged to be tested by a police officer with an official breathalyser kit.
To make sure my results are genuine, I'd previously arranged to be tested by a police officer with an official breathalyser kit.
Flashing light
Flashing light
It's known as a Police-issue Electronic Screening Device (ESD) and works on the traffic-light system. Green means no or very little alcohol in the system, amber means you are close to the limit and red says you are over it.
It's known as a Police-issue Electronic Screening Device (ESD) and works on the traffic-light system. Green means no or very little alcohol in the system, amber means you are close to the limit and red says you are over it.
Taking the official test, courtesy of the Met Police"Blow into the tube, as if you are blowing up a balloon," says PC Chris Lavender, who conducts the test.
Taking the official test, courtesy of the Met Police"Blow into the tube, as if you are blowing up a balloon," says PC Chris Lavender of the Osterley Safer Neighbourhoods Team, who conducts the test.
Again the light flashes green. To make sure, I'm re-tested twice and the light is green both times.
Again the light flashes green. To make sure, I'm re-tested twice and the light is green both times.
It's a vindication of the message that everyone is different, says PC Lavender.
It's a vindication of the message that everyone is different, says PC Lavender.
But even that is only half the story, says Dr David Sadler, from the Department of Forensic Medicine at Aberdeen University. On another day, I could have been over the limit.
But even that is only half the story, says Dr David Sadler, from the Department of Forensic Medicine at Aberdeen University. On another day, I could have been over the limit.
Not only is everyone different, the same body can react in different ways on different occasions, says Dr Sadler.
Not only is everyone different, the same body can react in different ways on different occasions, says Dr Sadler.
"How inebriated people get comes down to the rate of alcohol absorption from the intestines and that's affected by so many things including food, drugs - even what mood you are in," he says.
"How inebriated people get comes down to the rate of alcohol absorption from the intestines and that's affected by so many things including food, drugs - even what mood you are in," he says.
"It's the same for eliminating alcohol, which is the issue with driving the morning after. The time it takes to sober up can be affected by so many things and often people simply don't give themselves enough time. The only fool-proof way to not drink and drive is simply to do one or the other."
"It's the same for eliminating alcohol, which is the issue with driving the morning after. The time it takes to sober up can be affected by so many things and often people simply don't give themselves enough time. The only fool-proof way to not drink and drive is simply to do one or the other."
Add your comments on this story, using the form below.
Add your comments on this story, using the form below.
