How tired is too tired?

Google ‘Why am I so tired?’ and you’re met with hundreds of thousands of articles, papers and stories. You quickly realise that you’re not alone in your sleepiness.

You may be feeling sluggish even after a good night’s sleep or you may suffer from insomnia and or sleep apnea; there are so many ways in which our health and safety can be compromised with both insufficient sleep and poor quality sleep.

The word ‘tired’ can mean many different things to different people. See for yourself below.

Drowsiness and fatigue are not binary

Even though people use them interchangeably, drowsiness, tiredness and sleepiness are different to fatigue.


If you’re snuggled on the couch after a busy week at work filled with deadlines and meetings, you might feel exhausted and ready to head to bed.


Illness (think chronic fatigue syndrome) or physical activities (like competing in a half-marathon) can leave you feeling fatigued with aching muscles.


Drowsiness, on the other hand, is the dangerous state right before sleep onset, where your body is actually fighting to stay awake. Being at this stage behind the wheel, where your concentration and reaction times are severely impacted, can have deadly consequences.

Tired vs alert: many shades of grey

It’s not as black and white as calling yourself ‘tired’ versus calling yourself ‘alert’…. There are many shades of grey, and it’s more appropriate to determine the risk of a drowsy driving incident rather than label a driver as alert or not.

JDS™ is a scale

The Johns Drowsiness Scale (JDS™) does not just confirm whether, ‘yes, you are tired’, or ‘no, you are not.’

Its 10-point scale mirrors the grey area mentioned above by providing a number that is on the drowsiness scale to determine your risk of a drowsiness-related accident.

How do you know if you’re too tired to drive?

I feel fresh at the beginning of my trip!

If you drive long distances for your work – either to work, for your work, or after work – you understand the way you feel at the beginning of a drive compared to the end (or even mid-way) can dramatically change. So even though you’re feeling fine at the beginning, you might soon be feeling tired, but how do you know if you’re too tired to drive?

Time of day you’re driving

Night time driving is risky for drivers.

Driving at times of the day or night where your body is naturally programmed to sleep can mean you’re driving while fighting against your body’s natural clock. Shift workers are especially susceptible to feeling drowsy at work, and even while travelling to or from a shift. (Read more about shift work disorder in this blog post.)

Quality of sleep you got the night before

We’ve all been there: we’ve tossed and turned through an almost unbearable night of little sleep, and boy are we paying for it today!

Getting less than six hours of sleep can increase your risk of falling asleep behind the wheel.

If you know you need to drive a long distance the next day, setting off on a family holiday, or commuting to your worksite, prepare your home, bedroom, family, and yourself for good quality sleep the night before.

Do you have any accumulated sleep debt?

Ever heard of sleep debt?

It’s real. And before you know it, you’ve accumulated hours of it. There are no financial plans around this kind of debt; the only way to repay it is through sleep.

Where are you driving?

Long stretches of road can become dull and monotonous, and if there’s nothing actively capturing your attention, like other cars, people, cyclists and traffic lights, you can begin experiencing the effects of driver fatigue.

Similarly, familiar routes you travel every day can feel pedestrian, and if you feel you’re not being actively engaging by your surrounds, you might feel drowsiness beginning to set in.

Are you too tired to be doing what you’re doing?

At home on the couch

This is a common scenario we refer to often as it’s something we have all experienced.

If you’re scrolling aimlessly on your smartphone as you read this on the couch, it’s not as important to know how tired you are and how susceptible you are to falling asleep. We’re all guilty of dozing off on the couch and waking up a little disoriented after a few minutes. In this scenario there is no immediate need to know how tired you are and how likely you are to fall asleep, unless you have difficulty falling asleep after a short nap.

At work

If you work in an environment or industry that requires you to drive for long stretches, operate heavy or expensive vehicles and machinery, and complete shift work, you are at risk of experiencing a drowsiness-related accident, not just at work…

…but on the way home, too

Our focus is on all-hour protection, that is, protection for people who work in high-impact, 24/7 industries. Many of these workers travel long distances to get to work, complete a demanding shift, and then may have to jump behind the wheel again for a substantial stretch to get home.

Despite what you may think, you actually cannot fight sleep, no matter how many cups of coffee you drink, how loud you turn up the radio, or how many car windows you open. Eventually sleep will win.

But how do you know that you are at risk?

That’s where Optalert comes in.

Our wireless glasses measure a user’s eyelid movement at an extraordinary rate of 500 times per second, and with decades of research behind our technology, the data collected is translated into a number from 1 to 10. This ranking is called the JDS™.

In fact, we are often incapable of accurately determining how tired we are, so even if you feel relatively awake, a JDS reading can tell if you are, in fact, at a medium or high risk of a micro sleep or associated drowsiness accident – even if you don’t feel like you are.

Eliminate the risk of a drowsy driving accident with Optalert.

Find out which Optalert product is right for your workplace. Click here to take the quiz.