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Definition of circadian rhythm

Aviation Mechanic General (AMG) practice question 15 of 16 on Human Factors. ACS element AM.I.L.K3 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONThe daily rise and fall of body temperature, blood pressure, heart rate, alertness, and attention in a regular pattern is known as

  1. Athe Hawthorne Effect.
  2. Bcircadian rhythm.
  3. Cphysiological stress.
Show the answer and explanation

Correct answer: B. circadian rhythm.

  • A — incorrect The Hawthorne Effect is the finding from illumination studies that motivational factors can significantly influence human performance; it is not a daily physiological cycle.
  • B — correct The handbook states that variables such as body temperature, blood pressure, heart rate, blood chemistry, alertness and attention rise and fall in a daily pattern, and that this is known as circadian rhythm.
  • C — incorrect Physiological stressors are conditions such as fatigue, poor physical condition, hunger and disease; they are not the name for the daily performance cycle.

BACKGROUND

In its discussion of fatigue, the Aviation Maintenance Technician Handbook - General (FAA-H-8083-30B) explains that a person's mental and physical state naturally cycles through various levels of performance each day. Body temperature, blood pressure, heart rate, blood chemistry, alertness and attention all rise and fall in a daily pattern, which the handbook calls circadian rhythm. A person's ability to work and to rest rises and falls with this cycle, and performing counter to the rhythm can be difficult. Shift work requires technicians to work during the low cycles of their natural circadian rhythm, which is one reason it contributes to fatigue.

STUDY TIP

Associate the term circadian rhythm with the daily cycle of physiological variables and remember that the handbook advises avoiding complex tasks during the bottom of the cycle.

KEY POINTS

  • Circadian rhythm is the daily rise and fall of body temperature, heart rate, alertness and similar variables.
  • Ability to work and rest follows this cycle.
  • Shift work forces technicians to work during low points of the rhythm.

SOURCES

  • FAA-H-8083-30B ch14 "Fatigue"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.