Drivers could be hit by a £100 fine and three licence points due to an upgrade to motorway cameras.
This applies to motorway drivers using a shut lane, normally marked with a red 'X' on an overhead sign.
Now National Highways, which maintains motorways and trunk roads, says it has improved its motorway cameras to catch drivers doing this.
On Twitter, National Highways said: "There's no eXcuse - don't ignore the red X.
"It's illegal to drive in a red X lane and motorway cameras can now automatically detect drivers who flout the law. You could receive a £100 fine and get three points on your licence."
Last month motorists on smart motorways started to face unlimited fines for dangerous driving in an overhaul of the Highway Code.
Drivers who do not abide by the updated rules could be hit with an unlimited fine, a driving ban and up to 14 years in prison.
A statement from the Driving & Vehicle Standards Agency said: "The changes made refer to guidance on smart motorways. A total of 33 existing rules will be amended and two new rules introduced”.
Any accident that occurs as a result of falling asleep at the wheel is usually classified as 'dangerous driving', explains RAC.
Dangerous driving is a driving offence, and a more serious one than 'careless or inconsiderate driving'.
The Highway Code sets out a number of rules and regulations that drivers need to follow for the safety of themselves and others while on the road.
Breaking these rules could lead to fines and in some cases loss of licence.
One of the rule changes is number 91, under the "Fitness to Drive" category which includes drivers getting sufficient sleep and where not to stop.
Aside from behaviours such as driving aggressively and ignoring traffic lights, it also covers "driving when unfit, including having an injury, being unable to see clearly, not taking prescribed drugs, or being sleepy ."
If you are found guilty of dangerous driving, you could be hit with an unlimited fine, a driving ban and up to 14 years in prison, depending on the seriousness.
What does the updated Rule 91 say?
This is what the rule says, with the updated parts in bold :
"Driving when you are tired greatly increases your risk of a collision. To minimise this risk make sure you are fit to drive.
"Do not begin a journey if you are tired.
"Get sufficient sleep before embarking on a long journey avoid undertaking long journeys between midnight and 6am, when natural alertness is at a minimum, plan your journey to take sufficient breaks.
"A minimum break of at least 15 minutes after every two hours of driving is recommended.
"If you feel sleepy, stop in a safe place.
"Do not stop in an emergency area or on a hard shoulder of a motorway."
The emergency area takes into account new definitions which have been brought in to better define rules around Smart Motorways.
