Twenty years ago, just past midnight, the American tank ship Exxon Valdez was slicing through cold black water, cutting a course through the Gulf of Alaska. Anyone who was an adult in the ’80s knows what happened next: a misjudged turn, a grounding on the reef and 258,000 barrels of crude oil spilling into the ocean.

The National Transportation Safety Board’s post-mortem on the incident makes for riveting reading, packed with figures and costs that leave you light-headed: damage to vessel, US$25 million; clean-up operations, US$1.85 billion. Yet a central concern of the report is sleep. The evening of the spill, the third mate on duty, Gregory Cousins, was documented as having returned to work after only four hours’ rest, following an already “stressful, physically demanding day”. Fatigued and under-slept, Cousins’ judgement was deemed impaired; he may even have fallen asleep at the wheel. All that spilt oil, and over lost sleep.

The cost of fatigue may have come in one hit in this case, but in most Western economies today, lack of sleep builds like slow-rising debt. In Australia, lost work productivity from sleep disorders and associated illnesses is estimated to be worth $1.7 billion every year. Sleep deprivation has become a way of life. On the internet, my friends’ status updates read like odes to warped sleeping patterns, modern-day haikus of despair and insomnia. “Currently eating breakfast at 2 am,” one writes. “This last week,” writes another, “a whole new sleep disorder has developed. Xanax was my happy ending.”

Dr Douglas McEvoy is a senior sleep specialist at the Queensland Sleep Disorders Unit, where patients stay overnight to have their brainwaves, heart rate and limb movements monitored – by wires attached to their body and scalp – while they sleep. Dr McEvoy concedes that his work is still considered an “unusual discipline” within the realm of medicine. “We’ve all grown up with the notion that doctors specialise in being physicians or surgeons. Sleep wasn’t an area of medicine until the last 20 years. If people had problems sleeping, it was seen as one of life’s minor inconveniences, not an illness.”

Most patients are referred to the Queensland clinic by their GP and are tested for sleep apnoea, a condition that affects anywhere between one seventh and one quarter of all middle-aged people. Apnoea is derived from a Greek word meaning ‘breathless’ – which is to say, it’s a pretty word for suffocation. Those typically afflicted are overweight men of middle years, the extra weight on their necks causing strain during sleep. When the muscles of their tongues and upper throats relax, the combined pressure intermittently shuts off their airways, forcing them to wake up. Some sufferers have been observed to wake over 800 times in a single evening. That quality of sleep makes for a hellish waking life.

“Some patients come in and tell me they don’t sleep at all,” Dr McEvoy says. “Other people have gone to sleep at the wheel. I’m talking at the moment to a 40-year-old man who has gone to sleep at the wheel twice in the last month, who has sleep apnoea. He’s had very strong warnings from me about the dangers of driving.” But Dr McEvoy’s warnings didn’t prevent this patient from running a red light recently. “He woke up to find everybody around him steaming, cars blowing their horns. It only took seconds.”

The rooms in which QSDU’s sleep studies take place have been recently refurbished: neutral walls, firm beds, IKEA-esque art, wall-mounted LCD televisions. With their blond wooden decor, they look like smart, comfortable, inner-city hotel rooms. During the day, when they aren’t in use, staff lunch there, sitting on the cushy chairs, gossiping and catching up. McEvoy is looking for the light switch in one room when the ensuite toilet flushes. The bathroom door opens and a female staff member tiptoes sheepishly out. These rooms are little pockets of domestic comfort, designed to imitate home.

Next door to each room, technicians interpret the sleep data. One of them is Jaclyn, a young woman who has worked at QSDU for four years. All day, Jaclyn looks at rows of shaking lines that resemble earthquake readings overlaid with messy embroidery. “It’s essentially pattern recognition,” she says, busily scrolling across eight hours worth of horizontally scrolling data. She says that when she first started this job, she would stare at these lines so closely, non-stop, that she’d see them at night, in her dreams.

Despite the graphs, charts and QSDU’s finely tuned equipment, Dr McEvoy admits that there’s still a lot about sleep we don’t understand. This means there is always going to be a small number of people he can’t help. “Someone might say, ‘Why can’t I sleep, doctor?’ We go through all the usual things then have to say, ‘I don’t know.’ Thirty percent of people out there have broken sleep every night, and sometimes we don’t know why.”

In other instances, Dr McEvoy precisely diagnoses the problem, but the patient refuses to address it. He once worked in regional clinics examining shift workers from central Queensland coalmines. These men worked 12-hour, irregular, rotating shifts: two days on, one day off; some during daylight, others at night. “Over a period of years, that just wrecks people’s sleeping rhythms, and they never get it back again. It’s gone,” he says.

In Dr McEvoy’s mind, the Exxon Valdez spill is an extreme example of the havoc caused by something as simple – and, at the same time, as complicated – as disturbed sleep. Since the 1989 spill, the Exxon Valdez has been patched up and sold and re-sold across several continents. Acquired by a Hong Kong shipping company last year, the tanker now sails as the Dong Fang Ocean and carries ore. While crude oil remains the world’s most valuable traded commodity, everyone is afraid of a repeat of history, and the Exxon has retired from that business for now. Maybe the crew would never have had a problem if they had shipped the world’s second most-traded commodity instead. That, of course, happens to be coffee.