Jet Lag in Military and Civil Aviation: A Review Study

Physiological or behavioral cycles are generated by an internal pacemaker with an oscillatory frequency of approximately 24.2 hours which are named as circadian rhythm. This internal pacemaker is located at hypothalamus as suprachiasmatic nucleus and control sleep-wake cycle, with wakefulness commonly promoted during daylight hours and sleep promoted during evening hours. The aim of this article is to provide a framework for understanding the biological basis of jet lag and recommend management strategies. Understanding jet lag can help us to address the broader problem of circadian misalignment, which has increasingly been associated with increased risk of cancer (colorectal and breast), metabolic diseases, cardiovascular dysfunction, mood disorders (depression), and cognitive decline. The current study is a review article based on the literature in the field of aerospace medicine. It is hoped that this presentation would be useful for those who are interested in aviation medicine. Jet Lag usually experienced by individuals who cross at least 2 time zones by intercontinental flights. Symptoms and signs usually reveal after 1-2 days of arrival in relation with circadian system complication and cause insomnia, sleepiness, general malaise, gastrointestinal upset (anorexia, indigestion and defecation disorders), neural (fatigue, headaches, and irritability) and cognitive impairments (concentration, judgment and memory disturbance), etc. Eastward travel requires an advance phase and these persons often complain about initiating sleep at early evening and being awake at early morning. Thus, eastbound travelers have difficult adaptation and worsen features rather than westbound travelers. The incidence of jet lag often has not been reported, so the accurate prevalence is uncertain. Due to the progressive development of aviation and intercontinental travels, the awareness about jet lag and its complications, prevention and treatment for all population especially aviators and medical groups are necessary.