Aviation Human Factor

Lecture 10: Sleep, Jet Lag & Fatigue in Aviation

SLEEP

Sleep What is it?

“The natural periodic suspension of

consciousness during which the powers of

the body are restored.”

3MedlinePlus Medical Dictionary

How much sleep do you really need?• Sleep requirements vary dramatically

among individuals (age and gender)• Newborns sleep as much as 20 hours/day• Children sleep 8-14 hours/day• Elderly sleep 6.5 hours/day

When determining sleep requirements, 3 main factors should be considered.

• The complexity of the job to be performed. The more complex the task to be performed, the more sleep required for the individual to execute the task

• The potential for loss from errors due to fatigue. Pilots require rest plans since flying is a dangerous endeavor with high potential for loss of life and high-tech equipment.

• The individual’s ability to function with little sleep must also be taken into account, since this ability varies from person to person.

Factors affecting sleep quality• Comfortable condition (noisy rooms,

temperature, lighting)• Alcohol and caffeine consumptions• Time of sleep (too long or too short), this

will disrupt the normal sleep circadian rhythm & cycle.

• Circadian changes can affect sleep, especially when you are trying to sleep at times your body is not ready for sleep.

Factors affecting sleep qualityOur sleep/wake cycle is closely tied to

our body temperature.

The duration and “quality” of sleep is dependent upon body temperature.

The important is the timing and quality of sleep, not the amount of sleep.

Circadian rhythms

• “Circadian rhythms” means 24 hours cycle in the biochemical and physiological process of humans.

• It also described as an internal biological clock that regulates our body functions, based on our wake/sleep cycle.

• It is important in determining sleep cycles, hormone production, cell regeneration, and other biological activities.

12 am 12 noon 12 am

3 - 5 am 3 - 5 pm

Performance level

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Human Performance

Human Performance

• Generally, the lowest performance, alertness, and mood occur twice a day: from 3 am to 5 am, and to a lesser extent, again from 3 pm to 5 pm.

• During these time periods, errors are more likely to occur in judgment and reaction time.

Factors affect the Circadian Rhythm

• Cycles of day and night• Ambient temperature• Meal times• Napping schedule and duration• Stress and exercise

Importance of Sleep• Lack of adequate sleeps and rest results in

sleepy and fatigued pilots.• Air crash research revealed that the unsafe and

dangerous situations can result from a crew that has not had adequate sleep.

• This is because, not enough sleep lead to harder to pay attention, slower reaction times, poorer coordination & confusion.

• In other words, lose sleep or disrupt the body clock, will impair every aspect of human performance(Examples: Judgment and decision making can be degraded by 50 percent and memory can be degraded 20 percent by sleep loss)

Importance of Sleep• Pilot must know that sleep is important as the body

muscles and brain can only recover by sleep.• Beside that, sleep functions to rest mental & physical

condition with gather again the new energy.• The important is not the amount of the sleep but the

quality of sleep. • After 6 to 8 hours working, they need to restore back their

energy in about 7.5 hours of sleeping. • So that, they are thinking well and highly focus during their

work. • If they are not having enough sleep well, they can

cover it by take some napping.

Napping

• When sleep is not available or shortened by

operational concerns, combat naps are an alternative.

• Napping is a good strategy for coping with sleep deprivation during continuous operations or other times when it is difficult to get a good night’s sleep.

• Even naps as short as 10 min are good to prevent the individual feeling more tired.

JET LAG

JET LAG• Jet lag is a temporary disorder that causes

fatigue, insomnia, and other symptoms as a result of air travel across time zones.

• Jet Lag only occurs when flying from East-West or from West to East. In other words when we change time zones.

• Traveling from west to east shortens the day• Whereas from east to west travel lengthens the

day. • Jet Lag does not occur form North-South and

vice versa because there are no time zones changes.

Time Zone Changes During Flight• Studies have shown that complex bodily

functions, such as those measurable by reaction time, performance and decision time are affected by rapid shifts through several time zones

• Without proper preparation and planning, it takes one 24-hour period per one hour shift in time zone to recover– Crossing 4 time zones = 4 x 24 hours to adjust bodily

cycles

Jet Lag

Jet lag is more evident if you fly from west to east because it is more difficult for your body to adjust to your “losing time”.

Why does jet lag occur?

• The cause of jet lag is the inability of the body of a traveler to immediately adjust to the time in a different zone.

• Thus, when a New Yorker arrives in Paris at midnight Paris time, his or her body continues to operate on New York time.

• As the body struggles to cope with the new schedule, temporary insomnia, fatigue, irritability, and an impaired ability to concentrate may set in.

• The changed bathroom schedule may cause constipation or diarrhea, and the brain may become confused and disoriented as it attempts to cope with schedules.

How jetlag can affect the pilots• Jet lag causes circadian (body clock) changes

conflict with the destination’s sunlight & activities.• Due to that, a jet lag sufferer

(pilot/crew/passengers) may experience poor sleep, fatigue, insomnia, headache, constipation, confusion, dehydration, and even memory loss.

• All these symptoms may reduce the pilot’s performance ( judgment, decision making)

• Thus, jetlag also directly will affect the flight safety.

Tips to Help MinimizeJet Lag• ➢ Adjust your bedtime by an hour a day a few days

before your trip to match the sleep schedule you will keep at your destination.

• ➢ Reset your watch to the destination time to help you adjust more quickly to your destination time zone.

• ➢ Drink plenty of water during your flight to avoid dehydration. Dehydration can make jet lag worse.

• ➢ Eat lightly but strategically. What you eat can have a direct influence on your wake/sleep cycle.

• ➢ Relax on the first day at your destination. give yourself a break and let your body adjust to the time change a little more gradually.

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FATIGUEFATIGUE

“The state of feeling tired, weary, or sleepy that results

from periods of anxiety, exposure to harsh

environment, or loss of sleep.”

Fatigue

Fatigue can be defines as extreme tiredness resulting from mental or physical

illness.

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Fatigue

• Fatigue is noted by aviation community for many years as having a strong impact on flight safety and efficiency.

• As length of fatigue increases, performance may decrease, consequently lead to aircraft mishaps.

Types of Fatigue

• There are TWO types of fatigue.• ACUTE ... short duration, recovered

with good nights sleep.• CHRONIC ... occurs over a period

long period of time, long recovery!

Acute fatigue

• Acute fatigue– Results from repeating tasks during long flights or

from numerous repetitive short flights– Very common– Healthy persons recover with rest / sleep– Symptoms

• Tiredness• Lack of Energy• Loss of coordination• Inattention to details

Chronic fatigue

• Chronic fatigue– Occurs when recovery time is insufficient– Overlapping with factors of acute fatigue

Causes of Fatigue• Lack of Restful Sleep- Unable to allow sleep to

take over.

• Works too hard.-Body used up great deal of Energy.

• Dehydration- Body lose a large amount of water.

• Caffeine- Too much caffeine keeps the body in a high degree of alertness, even to the point of being tense (unable to relax).

Causes of Fatigue

• Long hours of working.• High intensity of stress• Large temperature variations.• Noise and Vibration for long periods.

• STRONG lighting.

Symptoms of Fatigue

• Attention & concentration reduced- take longer time for make decision making.

• Short memory loss -quickly forgot command given by ATC.

• Fixation- focus one thing only, ignore other important.

• Feel or appear careless, uncoordinated, & confused

• Impaired communication & cooperation

Prevention of Fatigue

• Get adequate sleep• Maintain consistent schedules of sleep, daylight

exposure, and naps. • Control sleeping environment

– Sleep in darkness.– Control noise.– Control room temperature.

• Napping• Practice good nutrition

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