Driving on motorways causes millions of people to panic, research suggests.
The M6 is said to make motorists feel nervous
As many as one-third of drivers admit to being anxious while using motorways, with older and younger women said to be the most affected.
Around 12% of 1,078 motorists surveyed by the RAC Foundation said they went out of their way to avoid motorways.
Symptoms of "motorway anxiety disorder" include increased heart rate and raised blood pressure, making people more prone to mistakes, the foundation said.
Other symptoms are excessive sweating, tension, headaches, stomach cramps and digestive problems.
The most anxious 12% experienced anxiety levels more significant than if they were attending a job interview, visiting the dentist or going on a first date.
Professional male drivers between 28-55 tended to experience the lowest levels of motorway anxiety disorder, the foundation said.
Nervous drivers are more likely to make mistakes such as leaving the indicator on, driving at excessively low or fast speeds, staying in low gears and driving to close to the car in front.
UK'S SCARIEST MOTORWAYS
M25 - "the road to hell"
A1(M) - roundabouts
M4/M5 interchange - confusing signs
M1 junctions 28-32 - congestion
M6 Birmingham - traffic mixing
M4 Maidenhead - tailgating
M27 Southampton - foreign drivers
M8 Glasgow - slip road into fast lane
M4 Wales - Severn Bridge
M18 Doncaster - confusing junctions
Source: RAC Foundation
Sarah Forrow, campaigns manager of the RAC Foundation, described the anxiety levels as worrying.
She said: "For many nervous drivers who venture onto the motorway there is a high risk of a self-fulfilling prophecy.
"They drive in an indecisive way which reinforces
their fears, annoys other drivers, and can increase the risk of accidents on the motorway.
"We would urge anxious drivers to drive with a calm passenger, leave plenty of space between their vehicle and other vehicles, and practise their driving regularly."
But she added motorways are the UK's safest roads - drivers are seven times more likely to have accidents on urban roads.
Conrad King, psychologist for the RAC Foundation, said for people to experience anxiety on the motorway was "quite natural and understandable"
He said: "This anxiety becomes a problem when drivers fail to get enough practice on the motorways, and so don't ever fully eliminate their fears.
"Some drivers build up their fears so much that they
create new completely irrational fears which serve to reinforce their original anxiety."
He added anxiety can be managed through appropriate post-test driver training,
regular driving practice, breathing exercises and listening to
According to the poll, the M25 is Britain's scariest motorway, described by drivers as "the road to hell".
Roundabouts and changing road standards on the A1(M) make it the UK's second worst motorway.
Others in the top ten include the M4/M5 interchange north of Bristol, the M6 in Birmingham and the M27 near Southampton.