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Over 7.7 million drivers risk drink driving by relying on 'old wives tales'

Direct line
  • Seventy seven per cent of drivers believe a person’s size is an important factor in how quickly the body processes alcohol.
  • Twenty two per cent use a flawed alcohol units consumed and time since last drink calculation to determine if they under the legal limit to drive.
  • Research reveals gender, body size and time since last drink cannot determine how quickly you will be under legal limit the morning after.

Over seven million drivers* admit to playing a dangerous game the morning after a night of drinking, by relying on unfounded methods to calculate if they are within the legal alcohol limit to drive.

According to a study** by Direct Line car insurance and AlcoSense consumer breathalysers, drivers admit to believing in urban myths and old wives tales when it comes to how quickly the body processes alcohol. Nearly eight out of ten drivers (77 per cent) believe body size and seven out of ten (70 per cent) believe gender, both have an influence.

The research found drivers are using other techniques to try and trick their body and reduce their chances of being over the legal alcohol limit to drive in the morning:

  • Twenty five per cent drink lots of water before they go to bed
  • Eight per cent eat lots of food before they go to bed
  • Six per cent have a big breakfast and drink lots of coffee before they drive
  • Six per cent have their ‘own’ system

However, scientific research** undertaken by Direct Line, AlcoSense and The Transport Research Labs, has revealed there is no conclusive evidence that gender or body size influences how quickly someone will be within the legal limit the morning after the night before.

In the following example, taken from the study, a shorter and lighter female had nearly the same breath alcohol content (BrAC) at the end of a night out drinking as a larger male. In the morning the male participant was still over the legal limit to drive while the female was well below the legal limit, dispelling the common misconception about body size and the ability to process alcohol.

Participant A
Participant B
Weight (kg)
Height (cm)
BrAC at end of night (µg/100ml breath)
BrAC in the morning (µg/100ml breath)

Simon Henrick of Direct Line car insurance, said:
"Drivers are taking a huge risk if they are relying on rough calculations and unproven theories to see whether they are safe to drive their car the morning after the night before. Our study shows that, despite what people may think, there is no magic equation to work out if you are safe to drive the following morning. Our strong recommendation is that if someone has drunk the night before, they should not drive the following morning, unless they are able to test their blood alcohol content."

Hunter Abbott of AlcoSense consumer breathalysers, said: "This study demonstrates the varying alcohol processing times between different people and the risks which drivers are unintentionally taking with their own and other road users’ lives every day. Any alcohol affects your ability to drive; the only safe way to tell when alcohol has cleared your system is to self test with a reliable personal breathalyser like AlcoSense."

For Further Information contact:

Simon Henrick
PR Manager
Direct Line
020 8313 5965

Kevin Monks
01628 778885
AlcoSense spokespeople are available during the holiday season by calling 07770 421079

Notes to editors

*7.7 million drivers equates to 22 per cent of the 35.3 million full car driving licences nationwide (source: Department of Transport)

**Opinium Research carried out an online survey of 2,008 UK adults aged 18+ from 3 to 5 of July 2012. Results have been weighted to nationally representative criteria.

*** Participants recruited for the study were groups of friends who were planning a night out. A researcher, who was a friend of the group, accompanied them on their night out, recorded their alcohol consumption and measured their breath alcohol levels at the beginning and end of the night. Participants were free to choose the type and quantity of alcohol they consumed, and they were not constrained in terms of what time they started or stopped drinking. The following morning participants were driven to TRL and subjected to a series of tests, including half-hourly breath alcohol tests.

The analysis had the following objectives:

  1. To examine how participants’ breath alcohol levels changed over the course of the trial and identify any patterns that emerged
  2. To identify whether any cases showed an unexpected relationship between height, weight, gender and the rate of reduction of BrAC

Direct Line

Started in 1985, Direct Line became the first UK insurance company to use the telephone as its main channel of communication. It provides motor, home, travel and pet insurance cover direct to customers by phone or on-line.

Direct Line general insurance policies are underwritten by U K Insurance Limited, Registered office: The Wharf, Neville Street, Leeds LS1 4AZ. Registered in England and Wales no 1179980. U K Insurance Limited are authorised and regulated by the Financial Services Authority.

Direct Line and UK Insurance limited are both part of Direct Line Insurance Group plc.

Customers can find out more about Direct Line products or get a quote by calling 0845 246 3761 or visiting


AlcoSense™ is an award winning British manufacturer of consumer breathalysers developed to measure if you are near or over the UK drink driving limit. Working on the same principles as Police breathalysers, AlcoSense products won the 2011 What Car? Best Breathalyser under £40 and under £100 Awards.

AlcoSense is available nationwide from Halfords or direct from AlcoSense at and 0800 195 0088.

More Information at

AlcoSense spokespeople are available during the holiday season by calling 07770 421079

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