Sleep And Fatigue Flashcards
Describe the stages of sleep
There are five stages - the first four are normal sleep, and the fifth stage is Rapid Eye Movement (REM) sleep.
Stage 1 of sleep
Transitional phase between sleeping and waking, person begins to relax and slow rolling eye movements begin.
- Lasts 1 to 10 mins
Stage 2 of sleep
Lasts 10 mins
Stage 3 and 4 of sleep
Slow wave sleep
Stage 5 of sleep
REM sleep - when dreams are recalled
Describe the mechanism of sleep regulation
- Human body relies on circadian rhythms to regulate sleep
- Our natural cycle is 25 hrs, external factors such as light, social activities and meals adjust this to 24hrs
- Body temperature regulates sleep. Rising temp = waking up, falling temp = going to sleep
Describe the problems associated with sleep at abnormal times of the day.
When circadian rhythms is disrupted or thrown off, may feel groggy, disorientated and sleepy at inconvenient times. Linked of a variety of sleeping problems
What is sleep debt?
- Every hour you sleep, you are able to stay awake for two. If you keep awake more than you sleep enough for, you will eventually crash.
What is meant by sleep inertia, when is it most likely to occur and how long does it take to wear off?
- When you are woken up in the middle of REM, feeling very groggy.
- Takes on average 15 minutes to recover.
How do individuals differ in their requirement for sleep?
- Different ages require different amounts of sleep
- The individuals homeostatic mechanism that makes them feel sleepy and tells them when they have had enough sleep.
What are the effects of napping?
- If they are less than 45 minutes, they do not result in sleep inertia - this coupled with caffeine is effective.
What are the effects of caffeine?
- Short term solution and can be very effective when coupled with a nap.
What are the effects of taking sedatives?
- Act on central nervous system and may suppress mental alertness.
- Melatonin should not be taken without advice from a specialist.
- Sleep inducing drugs can be prescribed to cure only SITUATIONAL insomnia.
What are the effects of taking stimulants other than caffeine?
- If stimulants other than caffeine are required for a pilot to stay awake, then they are unfit to fly.
- “pep pills” impair judgement and cause a dangerous level of over confidence.
What is clinical insomnia?
Difficulty sleeping in normal circumstances - an inability to sleep when the body requires it.
What is situational insomnia?
Difficulty sleeping because the biological rhythms are disturbed due to travel and shift work.
Describe narcolepsy
Sufferers fall asleep even when involved in a situation requiring their full attention = not pilot career
Describe sleep apnoea
Temporary cessation of breathing during sleep, may cause the sufferer to wake often causing sleep deprivation.
Define fatigue.
Increased discomfort with lessened capacity for work, reduced efficiency of accomplishment, loss of power or capacity to respond to stimulation and usually accompanied by a feeling of weariness and tiredness.
Causes of fatigue
- Disturbed or insufficient rest
- Low humidity
- Glare
- Vibration
- Noise
- Anxiety
- Distubrance of biological rhythms
- Excessive physical or mental activity
Physical symptoms of fatigue
- Feeling tired
- Reduction in vigilance
- Growing and irresistible need to sleep
- Inadvertent napping
- Lethargy
- Slowed reaction time
Mental symptoms of fatigue
- Difficulties memorising information
- Lack of concentration
- Periods of inattention
- Slow understanding
- Tendency to forget information and actions
- Bad mood
- Poor decision making
- Apathetic
Explain the difference between acute and chronic fatigue.
Acute: Short term - easily recognised and fixed by not flying
Chronic: Long term - difficult to recognise, more severe, a pilot must stop flying
Methods of managing fatigue
- Well rested
- Good sleep habits
- High level of physical fitness
- Eating regular, balanced and nutritional meals
- Avoid excessive use of alcohol
- Good mental health
Define biological clock
Innate mechanics that controls the physiological activities of an organism which change on a daily, seasonal, yearly or other regular cycle.
Define circadian rhythm
Physical, mental and behavioural changes that follow a roughly 24hr cycle, responding primarily to light and darkness in an organism’s environment.
Define circadian dysrhythmia
Any disturbance in the circadian rhythm.
Define desynchronisation
- Transmeridian desynchronisation - change in time zones = jet lag
Define zeitgeber
- “time givers” - daylight and mealtimes
- Environmental cues that entrain our biological rhythms
Describe the central human physiological processes underlying circadian rhythm processes.
- Wake with increasing body temp, fall asleep with decreasing body temp
- Performance increases with an increases in body temp and decreases as temperature decreases
- Verbal and mental reasoning peak around midday
- Some physiological functions are suppressed at night
How do circadian rhythms affect pilot performance?
- When pilots are operating outside the regulated rhythm, performance decreases and the effect of circadian dysrhythmia will be more likely.
Explain the effects of circadian dysrhythmia and methods of managing these
- Increased reaction time
- Decreased attention
- Impaired memory
- Emotional irritability
To overcome:
- Spend time in daylight
- Plan sleep periods
- Ensure sleep area is comfortable
- Avoid mental and physical excercise before bed
- void alcohol and drugs - suppresses REM sleep
- Avoid adjusting to the new time one if there for less that 48hrs
What is the rate of adjustment to crossing time zones in both east and west directions?
- Faster travelling to the west than the east (easier to stay awake than force sleep)
- In general, the body will adjust to the new time zone at the rate of one or two time zones per day.
What is the impact of shift work on pilots performance?
- Circadian rhythms are only partially adapted to current work/rest schedule
- Sleep deprivation is a fact of life for commercial aircrew
- Fatigue can occur due to sleep deprivation
Describe how the biological effects of shift work can be minimised.
If rotating shift are unavoidable:
- Phase delay/advance - gradually change the time you sleep and wake
- Bright lights as mimic daylight
- Sensible napped
- Regular balanced meals and limited alcohol
Identify the principles of good rostering practice
Long haul:
- Consideration to the length and number of sectors to be flown
- Length of total duty
- Avoid rostering night flights following transmeridian flight
- Transmeridian flights should be altered with ones in the same Timezone to allow the circadian rhythm to reset
Short haul:
- 2 early starts 3 late finishes max
