Driver health
A person's fitness to drive can be affected by a medical condition, by temporary illness, substances such as alcohol and by the environment in which they work, drive and live.
Health impairments, such as stress, sleep disturbance, migraine, flu, severe colds and hayfever can lead to unsafe driving. Sometimes, the treatment for these conditions can also impair someone’s driving. Our advice highlights some of the factors that can make someone unfit to drive and the importance of assessing your fitness to undertake a journey.
Driver fatigue
Fatigue is a serious road safety issue. Research suggests that it may be a contributory factor in up to 20% of road collisions and up to a quarter of fatal and serious collisions. These crashes are often particularly severe because drivers who fall asleep cannot brake or take evasive action.
Sleepiness affects driving by:
- Increasing reaction times
- Reducing concentration and alertness
- Impairing decision-making
- Reducing awareness of hazards
When are fatigue-related crashes most likely?
The risk is greatest:
- On long journeys, especially on motorways and other monotonous roads
- Between 2am and 6am
- Between 2pm and 4pm
- After having less sleep than usual
- After drinking alcohol
- When taking medication that causes drowsiness
- Following long shifts or night work
Staying alert on the road
To reduce the risk of fatigue:
- Do not start a journey if you are tired.
- Get sufficient sleep before long trips.
- Plan regular breaks, with at least a 15-minute break every two hours.
- Avoid driving during periods when you would normally be asleep.
- If you begin to feel tired, stop in a safe place and drink two cups of caffeinated coffee and take a short nap. If you continue to feel tired, find a safe place to stop overnight.
Measures such as opening a window or turning up the radio may provide a temporary feeling of alertness but are not effective substitutes for proper rest.
Sleep disorders and medical conditions
Certain medical conditions can increase the risk of fatigue and affect driving ability. Sleep disorders such as sleep apnoea can leave drivers excessively tired during the day and increase collision risk.
If you experience persistent tiredness, excessive daytime sleepiness or suspect you may have a sleep disorder, seek medical advice. Many conditions can be treated effectively while allowing people to continue driving safely.
Other temporary illnesses, such as flu, severe colds, migraines, stress and hay fever, can also affect safe driving. In some cases, the medication used to treat these conditions may impair driving as well.
Alcohol, medicines and driving
Alcohol can make fatigue significantly worse, even when consumed below the legal drink-drive limit. Many medicines, including some treatments for colds, flu, allergies and hay fever, can cause drowsiness and impair driving.
Before driving:
- Check medication labels carefully.
- Follow advice about drowsiness warnings.
- Ask a pharmacist or healthcare professional if you are unsure.
- Never drive if you feel impaired by alcohol, medication or recreational drugs.
Eyesight and driving
Good vision is essential for safe driving. Drivers and riders must be able to read a standard number plate from 20 metres, using glasses or contact lenses if needed.
If you require corrective lenses to meet the legal eyesight standard, you must wear them every time you drive.
Look after your eyesight
Many eye conditions develop gradually and may not be obvious in their early stages. Regular eye examinations can help identify problems before they affect driving.
RoSPA recommends:
- Having an eyesight test at least every two years, or more often if advised by your optician.
- Seeking advice if you notice difficulty reading road signs or driving at night.
- Ensuring your prescription is up to date.
Driving at night
Poor vision and glare from oncoming headlights can make driving more challenging, particularly as we age. Drivers who experience difficulties at night may wish to reduce night-time driving and seek professional advice about their eyesight.
Tinted "night driving" glasses are generally not recommended because they reduce the amount of light reaching the eye and may make visibility worse.
Know your legal responsibilities
Drivers must notify the DVLA if they develop certain eyesight or medical conditions that affect their ability to drive safely. Failing to meet the legal eyesight standard can lead to penalties and, more importantly, increase the risk of causing a serious collision.
Before you set off
Ask yourself:
- Am I well rested?
- Am I free from the effects of alcohol or drugs?
- Am I taking any medication that could impair driving?
- Can I see clearly and comfortably?
- Am I physically and mentally ready for this journey?
If the answer to any of these questions is no, delay your journey or consider using an alternative form of transport.