Where's your head at? How tiredness can affect your driving

Tired male yawns at breakfast table before working day.

Published 9 April 2021
Last updated 9 April 2021

We discuss the importance of sleep and how a lack of it can affect our health. We look at how tiredness can affect your driving, and provide tips on staying safe.

How much sleep did you get last night? I hope you had enough and are feeling full of the joys of summer.

You got rhythm

It may seem obvious, but sleep is absolutely essential to us. During a healthy night’s sleep, your brain will go through various stages and to various depths of sleep in approximately 90-minute cycles. This is part of our circadian (or daily) rhythm.

During the deepest sleep, your body restores itself: tissues grow and repair, your memory consolidates and you should wake up feeling fresh and ready to concentrate and make decisions.

How much do you need?

Most adults can manage perfectly well on 7 to 8 hours of good sleep a night. But teenagers need about 9 hours and, because they tend to fall asleep later, yet may have to get up for school, uni or work in the morning, they’re probably not getting enough sleep. Does this sound familiar?

Sleep deprivation

You’re probably familiar with feeling grumpy, forgetful and distracted when you’re tired, but did you know that the following things are also related to chronic (long-term) sleep deprivation?

  • Weight gain – if you’re tired and feel you need more energy, you’re likely to eat more than you really need, which will cause you to gain weight.
  • Increased sleepiness – this means that you’re likely to fall asleep more quickly if the opportunity presents itself.
  • Sleep apnoea – this is when you stop breathing for a few seconds in your sleep. It can happen up to 30 times an hour and you may not even know it’s happening. It interrupts your circadian rhythm, so you wake up from a disturbed night’s sleep feeling tired.
  • Micro sleeps – this is when your poor, tired brain decides to shut down for anything from a second to half a minute to get some desperately needed rest. It’s like a mini blackout and can happen whatever you’re doing – watching telly, sitting at a desk or in a lecture, or even driving a car.
  • Lack of attention or vigilance – sleepy people are often less responsive to what’s going on around them and may find it difficult to focus on a specific task.

Driving tired

A study in America in 2009 reported that 1 in 5 serious car crashes were related to sleep deprivation. Being sleep deprived has also been compared with being drunk when you’re behind the wheel: a person who drives after being awake for 21 hours is likely to perform worse than a person with a blood alcohol level of 80 mg per 100 ml (the UK drink-driving limit).

It’s unrealistic to say that you should only drive if you’re feeling super fresh, sharp and bouncy. But if you’ve had virtually no sleep the night before or you’ve been tired for a while, it’s probably best to think first before you drive for any distance or amount of time.

Tiredness can also be caused by sleep problems you might not know you have (for example, apnoea), so be aware of your usual levels of alertness and tiredness. If they’re not as they should be, you may want to look into the possible causes.

You’ll only be at your best if you’ve had enough sleep, so get your PJs on, snuggle down and remember

'Sleep is the golden chain that ties our health and bodies together.'

Thomas Dekker (Wiki page)

You can read more about sleep on the the Sleep Foundation website..

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