A Royal Navy Air Engineering Technician takes a rest

Staying alert, staying alive

Scientists alert military to problems of fatigue

Modern warfare demands optimal performance for long periods in frequently adverse conditions. Rigorous training develops physical and mental strength but without sleep the human body is unable to function and cognitive performance is impaired. Codex visited QinetiQ's Sleep Laboratory to find out why sleep is so important.

Lack of sleep continues to be a challenge during military operations and scientists and researchers seek to develop technologies and programmes that will help maintain cognitive performance. Long periods without sleep, disruptive sleep and changes in sleep patterns all take their toll on an individual's ability to perform and make decisions.

Research into the effects of sleep and how fatigue can be mitigated in extreme conditions has led to a deeper understanding of human performance and its limitations. The extremes of war may require ground troops to do without sleep for days at a time and pilots need to stay alert for long periods without any opportunity to sleep. Ground and support staff are equally challenged and decisionmakers also limit their own rest as they grapple with the demands of operations that require 24-hour attention and concentration.

One person who is acutely aware of the impact of sleep deprivation is Dr Barbara Stone, Technical Manager of the QinetiQ Human Protection and Performance Enhancement Group in Farnborough. Stone is in charge of the Sleep Laboratory which she believes is one of the best in Europe.

The state-of-the-art facility has individual environmentally-controlled bedrooms for the investigation of the sleepwakefulness continuum, circadian adaptation, the efficacy of hypnotics and the adverse effects of medication on vigilance and performance. They are also able to simulate occupational tasks such as train driving and radar control. They can monitor sleep and cognitive performance in the field with their portable EEG (Electroencephalography, the measurement of the electrical activity produced by the brain) recording systems which can record sleep, pharmaco-EEG and cognitive performance outside the laboratory.

The four individual bedrooms in the lab are generous in size and are temperature and humidity controlled at around 20 degrees. With the look of a budget hotel they are designed to be comfortable and, without windows, subjects enter a timeless haven where they may be required to stay for up to 30 days. The control room consists of a bank of screens where technicians keep a watchful eye over their sleeping charges, recording every twitch and listening to each breath as they sleep.

Stone explains that the work of her group has a number of applications: “We may be looking at jet lag, team performance or even what happens when people are isolated from light cues.” Although the lab is currently only involved in work with private organisations and businesses, Stone is aware her work is of interest to the military.

The controlled environment in the laboratory means she is able to research the effect of isolation from light cues (historically, research in this area involving Circadian Rhythms and the 'body clock' was done in caves). “The earliest studies showed that if you were isolated from all time cues then your body will 'free run' at a slightly longer length than 24 hours. This is because the natural length is 24.2 hours and each day it is synchronised mainly by light cues, but also by social cues. It was thought that humans wouldn't free run as the social cues were more important. This research is relevant to military personnel working in operation rooms under low light levels.”

Wired up for testing

Sleep inertia is another area which is of interest to decision-makers and most people will be familiar with the grogginess that affects awareness and performance immediately after waking. Stone and co-workers have been involved in work with the Civil Aviation Authority on this and explains that making decisions during this period can be of concern: “This inertia can last three to four hours, but mostly it is over in 20 minutes,” she explains.

“Normally when we wake up we have our breakfast, a shower and we don't need to drive until later so sleep inertia doesn't really matter. But for people on call who nap, such as the captain of a ship who may be expected to make decisions immediately after being woken, they could easily make mistakes. Military personnel do a lot of napping when they're in the field to make up for sleep deprivation, so the advice is to wake up at least 20 minutes before making a decision to get over sleep inertia.”

Napping

Stone explains that the consequences of sleep inertia can be poor decision-making or the inability to make decisions at all. “The more fatigued or sleep-deprived a person is, the worse the sleep inertia. Even with a nap you can go into a deep sleep and this takes time to dissipate.” Research into sleep inertia has revealed that there is a trade-off between the length of napping and the duration of sleep inertia and its effects. This means that a short nap results in less sleep inertia but less ability to maintain performance and a longer nap leads to greater sleep inertia but an increase in performance later on.

In operations, especially for ground troops, napping is the only way to have any sleep at all in some situations. For the severely fatigued this will mean falling immediately into the deep slow wave sleep phase and waking from this phase can result in human failure. Stone explains: “One of the reasons we are doing this work is to help airline pilots with their sleeping rhythms. Flight times and duty periods are worked out so that they shouldn't be tired on the flight deck but one of the problems is jet lag. If they are travelling round the world they don't always get the sleep that they should when they are away.”

Portable monitoring equipment means that sleep patterns can be recorded outside the laboratory and this has helped Stone and her colleagues get a better picture of the demands faced by commercial pilots. She is aware that military pilots face different demands but says that other aspects such as age also affect performance: “With airline pilots if they can't cope with long haul they may be able to move to short haul and this also has its problems as shift work, particularly night work, can be difficult for people over 40.”

Improved performance

Wired up for testing

So what is the best way to maintain physical and cognitive performance for the sleep-deprived? Although hypnotic drugs have been used to help people sleep during military operations, since World War 2 nothing has been used (apart from caffeine) to help them wake up. Stone suggests that scheduling can have a positive effect and she has worked with the Civil Aviation Authority and MOD looking at rosters and ways they can help create a better sleep pattern and improve performance.

Stone is also concerned that a lot of the younger recruits do not get enough sleep for their age and she points to research that has been carried out in the United States to make her point: “There has been work in the States on naval recruitment where a training scheme increased the amount of sleep they were getting and showed improvements in learning and discipline.”

Sleep is complex and even when there is opportunity, the ability to sleep may be lost. This, she explains, is particularly hard on operations: “Stress goes hand-inhand with conflict, and loud noise levels and the impact of war make it almost impossible for the land-based soldier to get sufficient rest. As well as vibration you also have sudden noises that can be even more disruptive. Some constant noises are manageable and even lull you to sleep (like the hum of air conditioning) but lots of irregular noise is difficult to sleep through.”

Add to this environmental factors such as extreme temperatures, type of shelter and altitude, and sleep becomes an even greater challenge: “We did some studies on the effects of altitude on sleep which may cause 'periodic breathing' which means that you keep waking up when your breathing stops for brief periods. This affects sleep and means that people who are affected feel tired the next day.”

Stone is convinced that the more we know about sleep, the better able we are to find ways to stay effective and alert during waking. Helping people adapt their sleep pattern and get sufficient rest is difficult but she is convinced that a greater awareness of the body's need for sleep will encourage people to repay their 'sleep debt'.

www.qinetiq.com

Research wakes up to need for sleep

In the United States, Defence Advanced Research Projects Agency (DARPA) has a Preventing Sleep Deprivation Program which is trying to find technologies that may help with cognitive performance in a military environment. They are looking at short-term approaches other than traditional stimulants such as caffeine.

By trying to understand the biochemistry following sleep deprivation they hope to find a way to maintain performance despite lack of sleep. They are also researching how nutrients and vitamins can support the brain and help with cognitive functioning. They are also investigating how other species, such as migrating birds, can stay alert during long periods and, through their research, hope to discover what happens to the brain when it is deprived of sufficient sleep.

Also in the US, the Walter Reed Army Institute of Research-Psychiatry and Neuroscience based in Silver Spring, Maryland, has a sleep deprivation research program that researches in field settings. It has an eight-bed sleep research suite equipped with polysomnographic monitoring equipment which gives a comprehensive recording of the biophysiological changes that occur during sleep as well as PC-based performance testing equipment.

The aim is to develop products that will sustain alertness and performance during periods of sleep loss. Looking at factors that determine the basis of individual differences in resilience during sleep loss, they are testing pharmacological strategies for reversing sleep loss-induced cognitive performance deficits, and developing a comprehensive sleep/ performance management program aimed at sustaining soldiers' performance during continuous operations.

http://wrair-www.army.mil/Psychiatry-and-Neuroscience/index.htm

Jet lag

Disruptions in Circadian Rhythm can cause jet lag, DSPS (Delayed Sleep Phase Syndrome) which creates a need to sleep longer, and ASPS (Advanced Sleep Phase Syndrome) which is the opposite and causes early sleeping and waking.

Night shifts can affect workers who find it difficult to readjust to normal night sleeping. Usually those affected are able to adjust after two weeks but, for some, the sleep disruption continues for longer. Most night workers never fully adapt because on their days off they revert to a normal day and night cycle. Jet lag is usually a temporary problem and, after a few days or a week, the body clock adjusts back to its normal rhythm. Usually the larger the time difference, the longer it takes to adjust. Some individuals find these disruptions cause them little problem while others find it difficult to adjust.

Pills have a place

Most professionals agree that if anxiety, heat, noise, time of day and other disturbances make sleep difficult, the occasional aid of a shortacting hypnotic may be beneficial.

Hypnotics, such as temazepam, have been used in military operations under medical supervision to ensure adequate sleep in critical scenarios, and it is clear that, if used judiciously, they are a significant force multiplier. The development of the ultra-shortacting hypnotic zaleplon opens up the possibility of sustained operations being supported by periods of rest of only four hours duration.

The benefits of prescribed sleeping pills for short-term use is accepted and medical advice should be sought as over-the-counter painkillers, antihistamines and decongestants (which may be used to encourage sleep) can affect performance adversely.

Crashing out

Tiredness can kill

Driving and Vehicle Licensing Authority (DVLA) issues guidance on the dangers of driving without enough sleep.

The facts

  • Up to one fifth of road accidents may be attributed to drivers falling asleep.
  • Driver 'inattention' is invariably due to drowsiness.
  • In sleep-related crashes, emergency braking is absent. 18-30 year old males are more likely to fall asleep driving late at night.
  • Long journeys at holiday times are more likely to cause fatigue.
  • 40% of crashes involve people who are driving to work.

Other factors include the body's inclination to sleep after a large meal and changes in body rhythm related to the time of day. There is also a natural tendency to feel sleepy during 'siesta' time and during the early hours of the morning.

DVLA suggests...

  • taking breaks on long journeys
  • being aware of and not ignoring the symptoms of fatigue
  • stopping when feeling drowsy
  • drinking coffee, followed by a short nap.

Short-term measures such as opening the vehicle's window or turning up the radio should only be used until a safe place can be found to stop.

IMPORTANT WARNING

In sleep-related crashes all drivers who fall asleep at the wheel have a degree of warning. There is no excuse for falling asleep at the wheel and it is not an excuse in law.

There are a number of medical conditions that cause excessive sleepiness. These may make driving unsafe.

These include:

  • Obstructive Sleep Apnoea (OSA)
  • illnesses of the nervous system, such as Parkinson's disease, MS, and MND
  • narcolepsy.

Medical conditions causing sleepiness must be reported to the DVLA. Safe driving depends on being alert and in control. Passengers and drivers should be aware of any signs that suggest that the driver is feeling drowsy. On long journeys, if possible, drivers should alternate with each driving a maximum of two hours.

www.dvla.gov.uk

Body clock basics

An internal biological clock keeps time even without cues from the environment. Because the time-keeping is not exact, the resulting rhythms in our physiology and psychology are known as Circadian Rhythms (from the latin 'circa', about, and 'dies', a day). Each day, cues such as light synchronise our rhythms with the 24-hour day.

Examples of such rhythms include body temperature, blood pressure, digestive activities and hormone production.

The internal biological clock is controlled by the hypothalamus in the brain. This is near to the optic nerve, explaining why light is so influential in sleep. Sleep is controlled by neurotransmitters, which act on nerves in the brainstem and the spinal cord.

The cycle of sleep and being awake in humans is dependent on light and temperature. Any changes can affect the cycle, and external factors such as alarms, changes in mealtimes, work or other demands can all take their toll.

The influence of the Circadian Rhythm during military operations can be significant and affect performance. This may include:

  • varying levels of alertness and ability to perform during different times of the day or night, the worst times being between 4 and 6am
  • impairment in performance in the late afternoon - sometimes called the post-lunch 'dip'. This is irrespective of meal timings and it has been suggested that a bi-phasic sleep-wake pattern may exist, since in siesta cultures there is a tendency to take a short nap between 3 and 5pm.

Circadian Rhythms may be modified by recognising that individuals may vary in when they work best and that motivation and effort may help mitigate any detrimental effect on performance.

Caffeine to the rescue

Research shows that caffeine found in many beverages and over-thecounter medications improves driver performance. It increases alertness although individuals who drink caffeinated beverages in the latter part of the day, particularly close to bedtime, may experience disturbed sleep. It may also shorten the length of daytime naps.

Heavy caffeine users who drink five or more cups per day may become tolerant and need larger doses to produce an alerting effect. Sudden withdrawal of caffeine from heavy users can produce adverse effects on performance and often results in headaches.

Drinking three cups of coffee (approximately 200mg caffeine) is effective in reducing sleepiness and driving incidents for up to 30 minutes in drivers who have been awake all night. In drivers who have taken five hours sleep, this same amount of caffeine significantly reduces incidents and subjective sleepiness throughout a two-hour drive.

As coffee is prepared in many different ways, the caffeine content per cup will vary. The consistent content of caffeine in recreational drinks such as Red Bull and pills may be more appropriate as a countermeasure to performance decrements. The wide availability of these and their convenience are also seen as positive considerations.

A preliminary study of the effects of Red Bull on levels of sleepiness in caffeine-deprived individuals showed that drinking one 250ml can containing 75mg caffeine is effective in reducing moderate levels of sleepiness such as the afternoon dip. This is effective for about an hour after being absorbed by the body and two cans eliminate moderate levels of sleepiness for about 90 minutes after being absorbed.