Circadian Rhythm
A circadian rhythm is a roughly 24 hour cycle in the physiological processes of living beings. The term “circadian” comes from the Latin circa, “around”, and dies, “day”, meaning literally “about a day.”
Body temperature, blood pressure, heart rate, alertness, and other body functions follow this roller coaster cycle.
The daily cycle’s two low points are typically 3 - 5 AM and again between 3 - 5 PM. These will be the body’s two natural low points of mental alertness regardless of the amount of sleep. This low point can shift, depending on sleep/wake times. During shift work, it will shift some, but the shift is countered by the natural regulator, sunlight.
Sunlight is the major regulator for our circadian rhythm. Goal: Try to avoid critical work during the two low periods.
Some Drugs and Medications
Some OTC drugs and/or prescriptions like allergy meds, antihistamines, may cause drowsiness. Many medications warn of NOT operating machinery or driving while using the meds; Can you name another OTC drug that typically does not come with a similar warning label?
Antihistamines have been among the most commonly involved medications contributing to serious aviation accidents. Those drugs were cited as contributing factors in 78 fatal accidents in the last ten years in Part 91 and Part 135 operations.
Large Temperature Swings
In a 2001 study, over 69% of the aviation respondents stated that “hot” temperatures and high humidities lead to a decreased job performance and the onset of workplace fatigue.
In addition, crewmembers reported that rapid temperature swings, as in repeatedly going from a warm hangar outside to the cold, increases the feelings of fatigue and overall “wear and tear” on the body.
6 4 5 23 1
12 noon
L 11 10 8 9 9 8 7 6 7
10 11 midnight 12 12
3 5 4
...They had little sleep on the night of the 2-3
January...both pilots had a meal that included some alcohol... each man
consumed five units of alcohol before retiring to bed.
21 CRM 2, TEM, Fatigue
CL-604, N90AG - Birmingham England - 4 January 2002 - 5 Fatalities
Excerpts From: Air Accidents Investigation Branch Aircraft Accident Report No: 5/2004 (EW/C2002/1/2) N90AG’s pilots should have been aware of wing
frost during pre-flight preparations but the aircraft was not de-iced and the ice detector system would not have alerted them. It was considered that the judgement and concentration of both pilots may have been impaired by the combined effects of a nonprescription drug (Diphenhydramine), jet-lag and fatigue.
Fatigue, Alcohol, OTC Drugs
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N
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I G
P
T R
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A
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G
H
O L
A
S
L A
L
T
E
E
E
R
E
I
S
G
S
H
E
E
R
T
A
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R
N
W
N
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H
S
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