Jet Lag and Circadian Rhythm Disruption

Jet lag occurs when travellers cross multiple time zones rapidly. This causes a mismatch between the body's internal clock (circadian rhythm) and the new local time. This disruption leads to various symptoms as the body adjusts.

Common Jet Lag Symptoms

Travellers often experience symptoms related to sleep-wake cycles and general well-being. Based on the effects of circadian rhythm disruption, common complaints include:

• A. Sleepiness during the day: The body's internal clock is still set to the previous time zone, making it difficult to stay awake during daylight hours in the new zone.
• B. Depression: While not always clinical depression, significant fatigue, mood swings, irritability, and feeling 'down' are common complaints due to the stress and sleep disruption.
• D. Impaired concentration: Sleep deprivation and the body's struggle to adapt can negatively affect cognitive functions, including focus and mental alertness.

Incorrect Symptoms

The following options are generally inconsistent with typical jet lag symptoms:

• C. Sleepiness during night: Jet lag usually causes difficulty sleeping at night (insomnia), not sleepiness.
• E. Sleeplessness during day: The primary sleep-related issue during the day is excessive sleepiness, not sleeplessness.

Conclusion

Considering the typical effects of jet lag, the most common complaints travellers face due to circadian rhythm disruption are daytime sleepiness (A), mood disturbances sometimes described as feeling down or depressed (B), and impaired concentration (D). Therefore, the combination of A, B, and D accurately represents common traveller complaints.