This morning on the way to work, lulled by the shrieks of school children and the rattle of the number 55 tram, I fell asleep. I don’t remember having a snooze – although I’m certainly tired enough to need one – but why else would I have failed to get off at my stop, or notice that my tram had reached the end of the line, turned around and was rattling back in the direction of my home?

One of the most disturbing facts in a fascinating documentary about fatigue is that, during a two-hour driving response test, a young, healthy subject whose sleep had been limited to three hours a night for the last few days, spent a total of 25 minutes asleep – that’s around 20% of the test. He had no idea that he’d slept at all and some of his micro sleeps occurred while he was actually driving the car: his eyes were open and he could turn the wheel and change gears, but his response times were dangerously slow because parts of his brain simply weren’t functioning.

As this might suggest, fatigue impacts poorly on the workplace in a number of ways. According to the "Dead Tired" documentary, tiredness:

• Accounts for 1/3 of all workplace accidents;
• Contributes to 1/4 of all road accidents;
• Results in lower productivity, or more presenteeism;
• Increases irritability, which may lead to more interpersonal conflict; and
• Can lead to higher rates of absenteeism, or lost time.

Sleep deprivation impacts poorly on mental health and this has implications for the workplace. In terms of the mind:

• Fatigue impairs cognitive functioning. When we’re tired, we’re less able to think laterally and therefore problem solving becomes more difficult.
• Sleep disturbance increases a person’s risk of depression by five. Problems with sleeping tend to be present before other symptoms of depression.
• A serious lack of sleep – for example, three hours of sleep a night for a week – can cause hallucinations similar to the kind you’d expect in a patient with schizophrenia.

Regularly missing out on sleep also has significant negative effects on physical health:

• Chronic sleep deprivation can cause diabetes, because too little sleep changes how your body regulates blood sugar.
• If we don’t get enough sleep, our immunity is reduced and our bodies become less resistant to disease.
• Sleep deprivation increases the risk of obesity. Tiredness drives us to eat more because it upsets the hormone balance: this makes us feel hungry AND stops us feeling full when we do eat.
• Too little sleep is bad for the heart and contributes to heart disease.
• Our bodies interpret sleep deprivation as stress.

Industries that require employees to drive or operate machinery need particularly vigilant sleep police. Beyond 16 hours of wakefulness, an individuals’ level of impairment is equivalent to a blood alcohol reading of 0.08.

According to some scientists, too many people in the western world are drunk drivers when it comes to fatigue. In order to help inoculate you against the fatigue epidemic, here are some facts about sleep and fatigue…

• As a general rule, we need 8 hours of sleep a night.
• On average, we get 90 minutes less sleep a night than people did 100 years ago.
• When we get less than 8 hours sleep a night, we build up a ‘sleep debt,’ which needs to be slept off.
• People’s responses to sleep deprivation vary widely – some people have very high levels of impairment with only a small reduction in sleep.
• Fatigue contributes to micro sleeps, which can range in duration from 3-14 seconds and which contribute to machinery and motor vehicle accidents.

The good news is that most of the health problems caused by sleep deprivation are reversible. When you get more sleep you also tend to become healthier and happier. Even heart problems can be resolved through better sleep. However, all the sleep in the world won’t undo the damage done by a fatigue related accident. There are some problems you just can’t sleep off.

This has stricken fear into the heart of at least one sleep deprived worker. Tonight, I'm planning on getting a solid eight hours in the sack. And hopefully when my tram rattles to a stop tomorrow morning, I'll notice!