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On a visit to a major chemicals plant, I was taken to admire its ultramodern
control room. Skilled technicians watched intricate graphics displays on
computer screens as the plant ran its continuous processes. This was high
technology at its most impressive. It would, and did, make a wonderful colour
photograph for the company’s annual report. I was there with some colleagues,
doing some training with the night crew, so we hung around and chatted with
them – about baseball, the weather, their jobs. As night came on and the
managers and engineers left, the lights were switched off ‘to rest the eyes’.
We sat there in comfortable chairs, the room lit only by the dim glow of
the monitors, and the temperature was adjusted up a notch as the crew settled
down for the night. It was peaceful, the only noise the soporific hum of
the computers as the plant smoothly split and purified molecules, filtering
and storing them.

With the setting so cosy we wondered how the crew managed to stay vigilant
through a 12-hour night shift. The answer was that they didn’t. ‘I just
set this baby up, pull my cap down over my eyes, and take in some z’s,’
said an operator. ‘It wakes me if it needs me.’ The next day we asked the
management team and the systems engineers to define the job requirements
of a control-room operator. Their reply was straight from the book. ‘The
job is to continuously and intently monitor the information on the screens
all night long,’ said one official. ‘It is much safer and more efficient
if operators closely manage the process rather than let the plant bounce
back and forth between high and low alarms.’

The official job descriptions had been written by people with no idea
of the pressures on the human body that night-time working causes. The plant’s
equipment and its management systems were designed by 9-to-5 staff, who
assumedthe operators would stay alert. They had no inkling that they were
creating a work environment where the operators, suffering the fatigue of
working a round-the-clock shift pattern, were bound to fail.

The managers responsible for this plant are not alone. Society generally
treats machines better than the bodies and brains of the people who run
them. A manager of an industrial plant, the pilot of a plane or space shuttle,
or the captain of an oil tanker would be deemed reckless if they operated
their complex machinery outside its design specifications. Yet the most
sophisticated equipment in that plant, aircraft or tanker – the human operator
– is routinely pushed beyond its limits.

People under stress don’t emit smoke or grind gears, but the signs of
breakdown are there just the same. Workers in round-the-clock industries
suffer a higher rate of illness and death than people who work only day
shifts. The major industrial accidents of our time have been rooted in fatigue
caused by asking people to perform outside their ‘design specification’.
Investigators have concluded that Chernobyl, Three Mile Island, and the
Swiss chemicals spill from the Sandoz factory in Basel that poisoned the
Rhine in 1986 probably would not have happened if those responsible had
been alert and well rested. In the Challenger disaster, NASA officials made
the ill-fated decision to fly the shuttle under the stress of staying awake
for 20 hours after only two or three hours’ sleep the night before.

Hospital horrors

But the problem is far broader than a few notorious accidents. In hospitals,
the wonders of high-technology medicine are rendered useless by the errors
of frazzled house officers on 36-hour shifts. On America’s highways, long-distance
lorry drivers work such irregular, sleep-disrupting schedules that accidents
in the hours just before dawn climb to 15 times the daytime rate. And pilots
worn out by long, monotonous hours in the cockpit, their brains jumbled
from crisscrossing time zones, inadvertently nod off in the cockpit and
drift off course, or land on the wrong runway. When such accidents are investigated,
‘human error’ is invariably held to blame.

Increasing knowledge about the neurophysiology of sleep and alertness
has yielded important insights into the causes of the fatigue that is endemic
to our nonstop, 24-hour society. This is helping researchers to develop
techniques that can sustain people’s alertness and performance around the
clock. For example, at the Institute of Circadian Physiology, a non-profit-making
research centre that my colleagues and I established in Cambridge, Massachusetts
in 1987, volunteers work day and night shifts at consoles identical to those
in industrial control rooms, and then sleep and relax in apartments where
we have complete control over temperature, light and dark, and other aspects
of the environment. Through such research, a field known as human-alertness
technology has begun to emerge.

Alertness is the optimal activated state of the brain. It is alertness
that lets us make conscious decisions about what to pay attention to in
our environment and what to screen out. It keeps us out of trouble – on
the road, in the cockpit, on the factory floor or on the trading floor.
And it is when we are alert that creative solutions to old problems pop
into the mind.

It is only in recent years that researchers have come to understand
that an elegantly engineered clock deep in the hypothalamus of the brain
governs alertness. The suprachiasmatic nucleus is a tiny cluster of nerve
cells, smaller than a pinhead, that regulates the timing of our bodies,
including cycles of sleep and wakefulness. This biological clock keeps track
of the time of day and the seasons of the year, and keeps body and brain
marching in step.

Formed over millions of years of evolution, the suprachiasmatic nucleus
is ill suited to the world of night work. Under the pull of our biological
clocks, most types of human performance – including manual dexterity, mental
arithmetic, reaction time, and cognitive reasoning – are significantly impaired
during the night-time hours. Each type of performance takes a downward turn
at bedtime, and recovers at dawn. That is not to say we cannot function
at night. We are simply more likely to make mistakes.

The suprachiasmatic nucleus appears to work through the body’s two
‘autonomic’, or automatic, nervous systems. In the words of Walter B. Cannon,
the Harvard Medical School physiologist who first described them at the
turn of the century, these nervous systems regulate all the essential functions
that ‘nature saw fit to remove from the caprice of an ignorant will’.

The sympathetic nervous system is the one automatically triggered in
the face of danger: it makes the heart pound, the blood pressure rise, the
pupils dilate, and the hair stand on end. This is what Cannon described
as the ‘fight or flight response’. Alertness is at its peak when the sympathetic
nervous system is fully activated. The counterbalancing mechanism is the
parasympathetic nervous system, which switches you into a relaxed state,
constricting the pupils and decreasing heart rate and blood pressure, so
bringing alertness to its lowest ebb.

Our state of alertness depends on which of these two nervous systems
dominates, which in turn is influenced by a variety of factors, of which
our circadian clocks are but one. Researchers have identified nine key internal
and external conditions that trigger alertness . Understanding what flips
these ‘switches on the control panel of the mind’ on or off is the secret
to ensuring that workers are clear-headed enough to do their jobs safely
and productively.

Contrary to their designers’ intentions, most industrial workplaces
flip these switches of alertness in the wrong direction. One reason is that
people’s quite understandable desire for comfort tends to be given precedence
over the need for alertness. The cosy scene in the chemical plant’s control
room described at the beginning of this article is duplicated all over the
world in air-traffic control towers, military installations, power plants
and oil refineries. Engineers are still striving to build more comfort into
the latest planes, locomotive cabs, trucks and process control rooms in
the mistaken belief that comfort improves performance. The truth is that
to be fully alert one has to be a little uncomfortable, especially in the
small hours of the night.

Managers also assume that a worker’s performance improves as their workload
and distractions decrease. That may be true to a point, but remove too many
distractions, reduce the workload too far, and monotony sets in. With little
to do in the middle of the night, the shift worker can easily be engulfed
by waves of sleep.

The design of most equipment, systems and work spaces for round-the-clock
operations should incorporate technology that optimises alertness, and therefore
performance, at any time of day or night. Based on an understanding of how
to manipulate the nine physiological switches of alertness, such technology
can help people cope better with shiftwork, or help provide equipment that
makes shiftwork easier to cope with. Both approaches are now being adopted
in a variety of industries.

Training programmes can teach people who work rotating or irregular
shifts how to adjust their sleep patterns. Workers can learn strategies
for getting better daytime sleep – say, by installing darkened blinds, arranging
ways to keep their families quiet, and encouraging spouses to form support
networks for peace of mind during their partners’ absence.

Resetting biological clocks

It is also possible to improve work and rest schedules to reduce conflict
with the human biological clock. For example, managers can shift employees’
work hours gradually, rotate hours clockwise – the direction in which the
body is better able to adapt to the night shift – and allow enough days
off between changes in a shift. One way to gain this extra time is to adopt
a 12-hour working day and to alternate between three and four working days
each week.

Computer models that take account of the factors that determine alertness
can help consultants identify the risks of a specific job or shift, and
suggest modifications. Relevant variables include circadian time of day,
and the amount of sleep the previous night and over the previous week. Plugging
these numbers into the computer model provides a prediction of how error-prone
a given worker is likely to be.

Another approach is to manipulate the light, temperature, sounds and
aroma of the work environment so as to encourage alertness. Of these four
factors, most is known about light. People turn down the lights at night
to avoid the discomfort of glare from reflective surfaces. Instead they
should be turning up the light to at least 1000 lux. Glare need not be
a problem. Computers can be equipped with nonglare screens, stainless-steel
coverings can be given a matt finish, and lights can be placed where they
are not reflected into people’s eyes. In control rooms where we have reduced
glare and installed bright lighting, we have seen dramatic improvements
in operators’ ability to function round the clock. They perform better on
reasoning tests, for example, and have trouble falling asleep even if they
try.

Controlled exposure to still brighter light, of 3000 lux or more, can
reset the brain’s circadian clock and so shift the body’s natural patterns
of sleep and wakefulness. This approach can be effective in combating the
jet lag caused by travel across time zones. I have helped to develop a computer
model that calculates the timing of the light dose for a particular traveller
based on data such as their normal sleeping and waking schedule, the point
of departure and destination, and the time of day and season of the year.
Travellers wear special glasses at times when they need to avoid bright
light, and a portable light visor to provide the timed light dose. This
technique brings a person’s internal body time rapidly into sync with the
new time zone. Without help, for instance, a person may need a week to
recover after flying eastwards from London across eight time zones to Tokyo;
with light treatment, the readjustment may take just two days.

Very bright light can similarly be used to reset the circadian clocks
of shift workers each time their shift changes, but here there are additional
problems. Some people whose body clocks have been switched in this way to
suit night work appear to have difficulty in readjusting to a normal pattern
of daytime activity, and so need a repeat treatment. Frequent air travellers
might need to have their circadian clock reset a handful of times a year,
but a shift worker rotating between day and night work every three or four
days, as many do, may have to switch fifty times a year. The long-term effects
of such frequent clock shifting are not known.

A less drastic, and often more effective solution is to build light
systems into the working environment that provide about 1000 lux. This is
bright enough to suppress drowsiness, and only has a small effect, if any,
on the biological clock. Many small manufacturers have developed compact
‘light boxes’ that deliver this level of illumination for individual use,
and the technology is beginning to be installed in a variety of industrial
control rooms.

Stimulating smells

Similar methods are under development for controlling temperature, sound
and aroma. The Japanese construction firm Shimizu, for example, has developed
special conference rooms in which not only light and temperature are regulated
but which also have special ventilation systems that periodically waft in
smells that can stimulate alertness.

No matter how much has been done to design a workplace, its equipment
and the workers’ shift patterns to keep alertness at a maximum, there is
no guarantee that people will not fall asleep on the job. This is where
the expanding of ‘human-alertness monitoring’ comes in. Its purpose is to
provide a warning when drowsiness sets in and to take action if necessary.

The most popular, but most primitive, approach to monitoring alertness
is the fitness-for-duty test applied at the start of a shift. Such tests,
which often consist of a series of tasks to be performed on a computer,
may be effective for screening out people seriously impaired by drugs or
alcohol, but they leave much to be desired in detecting fatigue. The stimulus
of the test itself may improve an individual’s alertness enough for them
to pass the test, even though they would be unable to perform their normal,
monotonous job satisfactorily. What’s more, alertness can deteriorate rapidly.
Someone fit for duty when they sign on at 11 pm may be seriously impaired
by 3 am.

In jobs where lives are at stake, the only reliable solution is to monitor
a worker’s alertness continuously. One way of doing this is to track brain
waves and eye movements, to reveal brief ‘microsleeps’ intruding into the
waking state, slow rolling of the eyes and changes in blinking patterns
– measurable signs of drowsiness. Researchers have wired up workers in a
range of occupations with scalp electrodes and portable Walkman-sized electroencephalogram
(EEG) and electrooculogram (EOG) recorders to detect changes in brain waves
and eye movements throughout a normal shift.

But there is some way to go before such alertness monitoring can be
put to everyday use. First, the measurement equipment must be unobtrusive
enough not to interfere with the job. Secondly, measurement must be done
in a way that doesn’t require a trained technician. Thirdly, any drowsiness
must be detected quickly – within seconds when a driver or pilot is involved,
if warnings or countermeasures are to be triggered fast enough to prevent
an accident. Fourthly, the system must be reliable. Failure to detect drowsiness
could have serious consequences, especially if workers come to rely on the
system to monitor their alertness. False positives are likely to be annoying
and will tempt people to switch the system off. Fifthly, the equipment must
be light enough to be carried around or fitted into a cramped vehicle. And
finally, it must be cheap enough to be installed in millions of sites and
vehicles.

Two approaches to alertness monitoring seem promising. One system, which
uses a lightweight EOG monitor resembling a telephone headset, has sophisticated
electrodes that do not need to be pasted to the head, and analyses a subject’s
eye movements in real time, looking for symptoms of drowsiness. The headpiece
does not restrict the wearer’s movement, but at the moment normal muscle
activity interferes with the software.

Even less obtrusive are devices that direct an infrared beam onto the
cornea and monitor the reflections to track eye movement, line of gaze,
blinking, and other ocular variables. Such eye-tracking technologies have
been used in ergonomic research on the design of cockpits and other human/machine
interfaces. Before they can be used as effective alertness monitors researchers
will have to work out which ocular variables are most useful for revealing
drowsiness. Another problem with these systems is their limited field of
view, and the difficulties of coping with movement of the subject’s head.
A possible solution is to use servo-tracking cameras that follow the subject’s
eyes.

When these problems are solved, eye tracking will provide monitoring
that is truly unobtrusive, doesn’t require workers to wear a special device,
and is so specific in its monitoring that it will be able to determine
whether the person has read an instruction or warning in one corner of
a computer screen.

The immediate goal of alertness monitoring is to sound some kind of
an alarm when an individual’s level of alertness is dangerously low. Such
a system might warn the individual concerned, their supervisor or a colleague,
or perhaps instruct a computer to assign a test task that would confirm
that the person was no longer alert. But eventually the system may not have
to tell anybody: one of the most exciting areas of research seeks to adjust
workers’ alertness switches automatically. This will be the key to devising
a truly human-centred workplace.

Imagine a future operator seated at the controls of a high-tech plant
in the small hours of the night. She is well trained in sleep and alertness
management, but the work is monotonous that night and her alertness starts
to wane. Unobtrusive infrared eye-tracking technology or a lightweight head-mounted
monitor picks up the first signs. Without her noticing, the brightness of
the illumination in her glare-free room is automatically increased, and
the layer of air at head level is cooled. A stimulating aroma wafts into
the room, while the computer flashes a low-priority but interesting task
onto her screen. Instead of slipping into a zombie-like state, she is restored
to full alertness, and is once again up to the task of coping with an emergency,
should it arise.

All the separate bits and pieces of such a system have reached at least
the prototype stage and are ready to be refined and combined into a smoothly
coordinated work environment. When such technology becomes a standard feature
of 24-hour operations, our society will finally have reversed the tendency
that leads to so many industrial breakdowns and disasters.

Martin Moore-Ede is an associate professor of physiology at Harvard
Medical School. His latest book, The 24 Hour Society: the Risks, Costs and
Challenges of a World that Never Stops, which contains many case histories,
is published by Piatkus (London), price £18. This is an edited version
of an article that first appeared in last month’s issue of Technology Review,
which is published eight times a year by MIT. Martin Moore-Ede/Technology
Review. Distributed by New York Times Syndication Sales.

* * *

The nine switches of alertness

Danger

Nothing snaps you out of a drowsy state faster than realising that you
are, or were, in danger. The sympathetic nervous system kicks in, placing
the brain on full alert. For people working in jobs where safety is paramount,
a controlled level of anxiety – or at least concern – can help optimise
their performance.

The stimulus does not have to be extreme. An interesting task, an exciting
idea can trigger a similar response. Conversely, if the job is boring or
monotonous, alertness fades. Parasympathetic drowsiness is triggered by
an endless stretch of highway across desert or the night shift in a plant
that is running smoothly.

Exercise

Mild activity such as taking a walk, stretching or even chewing gum,
keeps people awake. Vigorous activities like running or lifting weights
can stimulate alertness for at least an hour afterwards: it is hard to fall
asleep straight after a jog. The trouble is that many of life’s most dangerous
tasks, such as driving a car, flying a plane or directing air traffic, are
sedentary.

The biological clock

Alertness varies naturally in a daily cycle as your biological clock
wakes you up by activating the sympathetic nervous system, then starts shutting
you down by bringing in the parasympathetic system. These mechanisms, so
perfectly attuned to the normal traditional pattern of daytime wakefulness
and night-time rest, get us into trouble when we want to live according
to a different pattern. The biological clock is slow to adjust to any newly
imposed schedule: as you try to force yourself into a new time zone or a
changed shift pattern it may trigger alertness when you need to sleep, and
sleepiness when you need to stay awake.

Sleep

Quite apart from the influence of the biological clock, the urge to
sleep is driven by the number of hours since you last slept. Sleeping makes
deposits in your ‘sleep bank’; sustained wakefulness makes withdrawals.
When your accumulated sleep balance is running low, you will become drowsy
regardless of the time of day. Losing a couple of hours’ sleep for several
nights in a row will steadily erode your alertness. Similarly, the alertness
of night workers will be impaired if they have not had enough sleep during
the day. Of course, nothing replenishes the balance in your sleep bank account
like a good night’s sleep, but 10 to 20-minute catnaps can be effective
as well. Indeed, they restore alertness much more efficiently than a single
bout of sleep lasting as long as all the catnaps together, and make it
possible to reduce dramatically your total sleep in a 24-hour period.

Food, drink and drugs

A heavy meal may induce parasympathetic drowsiness; conversely, the
act of eating light snacks may help keep you awake. The intake of various
licit and illicit substances is one way to force alertness on a fatigued
brain. Shift workers drink coffee by the pot, rather than by the cup. Lorry
drivers take amphetamines to keep going, and in more innocent days hospital
doctors would revive themselves with small sniffs of cocaine. One of the
biggest problems with pharmacological strategies is the way the brain chemistry
rapidly adapts so, as time goes on, larger doses are needed to have the
desired effect.

Light

In the expensive restaurant where one lingers and pays appropriate parasympathetic
homage to a gourmet meal, the lights are turned down low, and the pace is
slow. Fast-food establishments are brightly lit to encourage fast eating
and a quick departure. Brighter lights of at least 1000 lux – equivalent
to the light level outdoors just after dawn – can dramatically suppress
sleepiness on the night shift, keeping workers in a state of sympathetic
activation. Unfortunately, industrial workplaces tend to be lit at only
10 to 100 lux at night, which does nothing to stimulate alertness.

Temperature

It is common experience that cool, fresh air, especially upon the face,
helps people to rouse themselves from a sleepy state. Sultry heat has the
opposite effect, which is why it makes little sense for industrial plants
to keep workers cocooned at night.

Sound

Some sounds can invigorate while others will lull you to sleep. Rolling
surf or the smooth rushing of a mountain stream are so relaxing that these
sounds are now electronically simulated in ‘white noise’ machines that some
people have installed in their bedrooms. Yet exactly the same electronic
white noise is produced by the equipment in industrial control rooms that
people are meant to watch intently through the night. In contrast, irregular
or variable sounds – like a door banging intermittently on a windy night
– will keep you awake. By the same token, a car radio can be a godsend for
anyone driving alone, and banning radios from a quietly humming industrial
control room is counterproductive.

Sound

Although less research has been done on olfactory stimulation than on
the other eight factors, evidence is emerging that certain aromas such as
peppermint make people more alert.