# Health and Hygiene

> Factors affecting pilot health and performance.

- **Subject:** 040 — Human Performance Limitations
- **Section:** 040-02 — Basics of Aviation Physiology and Health Maintenance
- **Topic code:** 040-02-03
- **Last reviewed:** 2026-04-01
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/human-performance-limitations/basics-of-aviation-physiology-and-health-maintenance/health-and-hygiene/

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## Intoxication
*   **Alcohol**: A central nervous system depressant. Affects judgment, vision, and balance.
    *   **Rule**: 8 hours "Bottle to Throttle" (often 12-24h recommended). Limit typically 0.02% BAC.
    *   **Histotoxic Hypoxia**: Alcohol interferes with oxygen use by cells.
*   **Tobacco**: Produces Carbon Monoxide (CO).
    *   **CO Affinity**: Hemoglobin loves CO 200x more than Oxygen. Reduces oxygen carrying capacity (Anemic Hypoxia). Smoking lowers performance altitude by ~5,000 ft.

## Fatigue and Sleep

![Biological clock human](https://upload.wikimedia.org/wikipedia/commons/3/30/Biological_clock_human.svg)

*   **Circadian Rhythm**: The body's natural 24-25 hour cycle (Body temperature drops at night, alertness drops 02:00-06:00).
*   **Jet Lag**: Desynchronization when crossing time zones. Worse flying East (shortening the day).
*   **Sleep Inertia**: Groggy feeling for 15-30 mins after waking up (especially from deep/slow-wave sleep).
*   **Management**: Strategic napping, bright light exposure, controlled rest.

## Decompression Sickness (DCS)
Caused by nitrogen bubbles coming out of solution (Henry's Law).
*   **The Bends**: Joint pain.
*   **The Chokes**: Lung pain.
*   **The Creeps**: Skin itching.
*   **Neuro**: CNS issues.
*   **Scuba Diving**: Should not fly for **12 hours** (non-decompression dives) or **24 hours** (decompression dives) after diving.

## Medication
Self-medication is discouraged.
*   **Antihistamines**: Drowsiness.
*   **Analgesics**: Can mask symptoms.
*   **Antibiotics**: Side effects + underlying infection.
*   **Consult AME**: Always consult an Aviation Medical Examiner.

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Free study notes from pilotsyllabus.com. Not a substitute for training at an approved ATO.