Driving when you are tired can be as dangerous as driving while you are drunk. Find out how important it is to be well rested before you drive and what you can do to stay safe and alert behind the wheel.
Key points about sleep and safe driving
- If you drive when you are tired, you risk your life and that of others on the road.
- In Aotearoa New Zealand in 2020, fatigue was a factor in 25 deaths and 113 serious injuries.
- The more time you drive while tired, the greater the risk you will have a crash. However, most fatigue-related crashes happen on trips that are under 2 hours and within 20 minutes of home.
- You are more at risk if you are young, a shift worker or have a sleep disorder. Alcohol and speed also increase your risk.
- You can avoid being a tired driver by preparing in advance and looking out for the warning signs of fatigue when you are driving.
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How does tiredness affect my ability to drive?
Driving tired can be lethal. Nodding off while driving means you won't brake before you hit anything. This puts you, your passengers and other drivers at huge risk. Even if you don't fall asleep, tiredness increases your reaction times and dulls your ability to pay attention to what is happening on the road.
Although the effects are not exactly the same, driving while you are drowsy is similar to driving while drunk, and equally dangerous.
- If you stay awake for 18 hours and then drive, you'll behave as if you have a blood alcohol level of 50 mg of alcohol per 100 ml of blood. That's the same blood alcohol level as Aotearoa New Zealand's legal drink drive limit for drivers 20 years and older, and it's way over the blood alcohol concentration level of zero for drivers under 20 years old.
- If you drive after staying awake for 24 hours, you're as dangerous as someone with a blood alcohol level of 100 mg of alcohol per 100 ml of blood – that's twice the legal blood alcohol limit for adults!
Tips for staying alert at the wheel
Consider whether you need to drive
- Especially for long journeys, is there another transport option to get you where you need to go?
Plan your trip
- Get plenty of sleep before a long journey.
- Don’t drive when you are normally sleeping, such as between 10pm and 6am.
- Stay somewhere overnight rather than travelling straight through on long journeys.
- Avoid driving after long-haul flights.
- Allow for rest stops to revive yourself.
- Take a break every 2 hours or every 100 km.
- Get out of the car and walk around.
Eat and drink sensibly
- Eat healthy meals of light, fresh foods at your usual times.
- Avoid large meals and fatty, sugary foods as these will make you feel sleepy.
- Drink fluids to stay alert – stay hydrated with plenty of water.
Get fresh air and conversation
- Allow fresh air to flow into your vehicle – don’t use the recirculating-air function.
- Talking to someone or listening to music can help you to stay alert.
Share the driving
- If possible share the driving.
- Don’t drive over your allotted driving hours.
Take care with medications
- Avoid taking any medications before you drive that will make you sleepy, such as travel sickness tablets, sleeping pills, cold preparations and some pain killers and antihistamines.
- Read drug information sheets to check for side effects.
Don't ignore warning signs of fatigue
It’s time to pull over and take a break if you start to experience signs of sleepiness while you are driving. These may include:
- finding it hard to keep your eyes open
- feeling sleepy and sluggish
- yawning or rubbing your eyes repeatedly
- lack of concentration, daydreaming or slow reaction times
- impatience, feeling restless and irritable
- difficulty focusing or holding your head up
- drifting over the centre line or road edge
- changes in your driving speed, going slower or making larger steering corrections
- lapses in attention, such as missing road signs
- ‘checking out’ for a few seconds (micro-sleep).
Micro-sleeps are involuntary sleeps caused by fatigue that only last a brief period, but can be very dangerous if they happen while you're driving. If you micro-sleep for just 1 second while travelling at a 100 km/h, the car will have gone 28 metres without you in control.
What should I do if I feel sleepy?
- Don’t hang on till you get to where you’re going. Pull over immediately in a safe place.
- Move to a passenger seat, lock the doors and take a power nap of 15–30 minutes.
- Don't sleep for more than 30 minutes or you will feel groggy when you wake up.
- Set an alarm or have someone phone to wake you up if you think you will oversleep.
- Walk around the vehicle when you wake up to help you become more alert.
- Wait at least 10 minutes after waking up before you start driving again.
- Fatigue Ministry of Transport, NZ, 2020
- Drowsy driving vs drunk driving – how similar are they? Sleep Foundation, US, 2022
- Drink driving limits in New Zealand Ministry of Transport, NZ
- Drinking and driving www.alcohol.org.nz
- Driver fatigue Waka Kotahi NZ Transport Agency