Sleep and Fatigue

Solution 2

The pilot has a short sleep (1 hour 20 minutes) and then enjoys the local nightlife. He/she has a further period of sleep to give sufficient credits before the third and final sleep period immediately prior to duty day.

State	Local Time	Body Clock Time	Sleep Credits
Sleep	2100 - 2220	0200 - 0320	2 hours 40 minutes
Awake	2220 - 0100	0320 - 0600	0
Sleep	0100 - 0500	0600 - 1000	8 hours
Awake	0500 - 1300	1000 - 1800	0
Sleep	1300 - 2100	1800 - 0200	16 hours

Advantages

•More sociable times to be awake.

•Both first and last sleep periods will be of good quality as credits are 0 and body temperature is on the decrease.

Disadvantages

•Very disrupted sleep pattern and it will be hard to stick to the schedule.

•Middle sleep period will be or poor quality as body temperature will be rising.

Sleep Hygiene

If your body really needs sleep it will sleep under almost any condition. If one is attempting to sleep whilst still in sleep credit or at a time of low circadian sleepiness then:

•Avoid drinks containing caffeine near bedtime (coffee, tea, cola and a number of fizzy soft drinks). Caffeine affects both Stage 4 and REM sleep. When caffeine is removed from a drink, the sleep-disturbing effect is also removed. (Aspirin also contains caffeine).

•Avoid napping during the day.

•Make sure the room and bed are comfortable, with any daylight excluded, air conditioning working, and ensure insects (especially the biting or stinging variety) are not able to enter the room.

•Avoid excessive mental stimulation, emotional stress.

•A warm milky drink, light reading, or simple progressive relaxation techniques will all help to promote sleep.

•Avoid alcohol and heavy meals.

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Sleep and Alcohol

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Alcohol is widely used by aircrew as an aid to sleep. It is however a non-selective central nervous depressant. It may induce sleep but the sleep pattern will not be normal as REM sleep will be reduced considerably and early waking is likely.

Sleep Disorders

Narcolepsy

An inability to stop falling asleep even when in sleep credit. Specialists believe that this is associated with the inability of the brain to distinguish between wakefulness and REM sleep. This condition is clearly undesirable in aircrew as the sufferer may go to sleep at any time, even in a dangerous situation.

Apnoea

A cessation of breathing whilst asleep. This is quite a common condition and the subject will normally either wake up or restart breathing after a short time.

It becomes a more serious problem when the breathing stoppage lasts for up to a minute and the frequency of stoppages increases. The frequent awakenings will disturb the normal sleep pattern and the individual may experience excessive daytime sleepiness. Other clinical problems may be involved and medical advice should be sought.

Sleepwalking (Somnambulism)

This condition, as well as talking in one’s sleep, is more common in childhood, but does occur later in life. It may happen more frequently in those operating irregular hours or those under some stress. The condition should not cause difficulty in healthy adults unless the sleep walker is involved in an accident whilst away from his bed. Sleepwalking, as night terrors, happens during non-REM sleep.

Insomnia

This is simply the term for difficulty in sleeping. It may be divided into:

Clinical Insomnia

This describes the condition when a person has difficulty in sleeping under normal, regular conditions in phase with the body rhythms. In other words, an inability to sleep when the body’s systems are calling for sleep.

It must be understood that clinical insomnia is rarely a disorder within itself. It is normally a symptom of another disorder. For this reason the common and symptomatic treatment with sleeping drugs or tranquillisers is inappropriate unless treatment for the underlying cause is also undertaken.

Situational Insomnia

There is an inability to sleep due to disrupted work/rest patterns, or circadian dysrhythmia. This often occurs when one is required to sleep but the brain and body are not in the sleeping phase. This condition is the one most frequently reported by aircrew.

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Drugs and Sleep Management

People’s tolerance to sleep disturbance varies and some individuals may require the assistance of drugs to obtain sleep or to stay awake. The commonest drug used to delay sleepiness is caffeine, contained in tea or coffee, and this will assist the user to stay awake.

Wide publicity has been given to melatonin as a cure of jet lag. Aircrew should not take this drug or any other drug or medicine without first seeking advice from his/her aviation medical specialist.

Barbiturates and benzodiazepines (valium, mogadon, librium and normison) must be rigorously avoided. Barbiturates are not only addictive but fatal if taken in overdose. Contrary to common belief, benzodiazepines can be addictive and all have an adverse effect on performance - especially if taken with alcohol. There is no place in aviation for such drugs except under the strict supervision of an aviation medical specialist.

Fatigue

Introduction

Fatigue is deep tiredness and, similar to stress, it is cumulative and can be caused by:

•A lack of restful sleep.

•A lack of physical or mental fitness.

•Excessive physical or mental stress and anxiety.

•Desychronisation of the body cycles (jet lag).

Whereas tiredness is instantly recognisable by the sufferer and is an acceptable social admission, fatigue is more insidious. A pilot suffering from fatigue can be unaware of his/her condition for a long period of time until a crisis forces realisation. Even if aware that fatigue is a problem, a pilot will be hesitant to admit the fact openly. It appears to be akin to an admission that he/she is not up to the job. It is critical to be able to recognize the symptoms of fatigue both in yourself and, just as importantly, in other members of your crew.

Fatigue can be subdivided into short and long-term (chronic) fatigue.

Short-term Fatigue

As implied, this type of fatigue is akin to tiredness. It is usually due to a lack of sleep, hard physical or mental exertion, crew scheduling, a long duty period, lack of food or jet lag. Shortterm fatigue is easily recognized and remedied by not flying and sufficient rest.

Long-term (Chronic Fatigue)

Long-term fatigue is much more difficult to recognize and admit. It can come from a number of different causes which may include a lack of physical or mental fitness, a stressful marriage coupled with problems at work, financial worries and a high workload. It also can be subjective, one pilot being able to tolerate more than the next before chronic fatigue sets in. Anyone who suspects that they are suffering from chronic fatigue must take themselves off flying.

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Sleep and Fatigue

Symptoms of Fatigue

The symptoms of fatigue can be:

•Lack of awareness.

•Diminished motor skills.

•Obvious tiredness.

•Diminished vision.

•Increased reaction time.

•Short-term memory problems.

•Channelled concentration.

•Easily distracted.

•Poor instrument flying.

•Increased mistakes.

•Irritability and/or abnormal mood swings.

•Reduced scan.

•Reversion to ‘old’ habits.

•Decrease in communication.

Delaying the Onset of Fatigue

Some of the actions that may be considered to avoid fatigue:

•Accept that fatigue is a potential problem.

•Plan sleep strategies proactively (plan sleep ahead of the next day’s activities).

•Use exercise as part of the relaxation period and ensure you are fit.

•Avoid alcohol.

•Eat a regular and balanced diet.

•Have your emotional and psychological life under control.

•Ensure cockpit comfort.

•Ensure that food and drink are available for long flights.

•Ensure your seat is properly adjusted.

Vigilance and Hypovigilance

State ofVigilance

The scientific definition of vigilance differs from what we normally understand by the term. The state of vigilance is the degree of activation of the central nervous system. This can vary from deep sleep to extreme alertness and is controlled by the circadian cycle. A vigilant man is an alert man and so, in normal circumstances, as workload increases so does vigilance.

Note: Vigilance is a very different mechanism to that of attention (see Chapter 7).

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Hypovigilance

This occurs when sleep patterns begin to show on an EEG during activity. It is akin to a microsleep which can occur during periods of:

•Monotony.

•Reduction of workload.

•During simple or repetitive tasks.

•Constant and monotonous noise.

•Low lighting.

•High temperature.

•Isolation.

•Sleep debit.

•Fatigue.

It can also occur shortly after a meal.

Forestalling Hypovigilance in Flight

It is not possible to totally eliminate hypovigilance during flight and, indeed, there is a theory that hypovigilance helps to control energy consumption. However, it is prudent to endeavour to forestall this phenomenon as far as is possible. Precautions should include:

•Ensure that you have sufficient sleep credit.

•Be aware of the physical danger signs which may include:

•Drowsiness, head dropping forward and a vague but persistent sensation of discomfort causing you to constantly shift your sitting position.

•Slower sensory perception (having to look at an instrument for a longer time than normal before digesting its information).

•Preoccupation with a problem completely outside of the current situation.

•Moodiness and a reluctance to talk.

•Move your position regularly every so often and, if possible, get up and walk a few steps in the aircraft.

•Maintain social contact with the rest of the crew.

•Vigilance decreases with lack of stimuli so keep mentally and physically active.

•Members of the crew should take their meals at different times. This goes a long way to ensuring that, if hypovigilance is to be a problem amongst the crew, its occurrence will probably be staggered. As has already been discussed, this precaution also avoids food poisoning striking more than one member of the crew at a time.

In general there is no absolute amount of sleep that must be achieved

You should sleep as much as you need

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