DAN Medical Frequently Asked Questions
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>(A newer version of this article is available.) Jet lag is a result of your internal body clock being out of sync with the day-night cycle at your destination when traveling. Updated February 13, 2018: See the latest jet leg information here .
>Long-distance travel in which humans cross several time zones in a short time can cause what is commonly known as jet lag, also called rapid time zone change syndrome or desynchronosis. This condition results from your circadian rhythm — your internal clock, which is attuned to the day-night cycle at your departure location — being out of sync with the day-night cycle at your destination with little or no time to adjust.
>Jet lag primarily affects air travelers because of the greater distances and time zones covered in a relatively short time. Boaters may have some difficulty with this condition if they do not make regular accommodations as they travel across the globe.
>Feeling sleepy, hungry and alert at the wrong times are common symptoms of jet lag, which may affect your social life and your ability to work, exercise or sleep. Fortunately, your internal clock will synchronize with your new environment within a few days. The more times zones you cross, the more intense your symptoms are likely to be and the longer they will take to diminish.A few days to a week before your departure, try to gradually move your bedtime to what it will be at your destination — i.e., if you are traveling east, where night comes sooner than at your departure location, go to bed one hour earlier than you usually would for as many days as the number of time zones you will travel through. To make it easier to fall asleep early, avoid coffee, tea, chocolate, alcohol and exercise for three to four hours before your new bedtime. Then wake up earlier in the morning and try to catch some sunshine to help your body's internal rhythm adjust. If you are traveling west, you should do the reverse routine — gradually go to bed and wake up later in the days leading up to your departure. Jet lag may be exacerbated by poor sleep during an overnight flight. Falling asleep on a plane can be difficult for several reasons. During sleep, your body temperature falls, and the activity of some hormones changes. This process usually occurs at a similar time every day, prompted by changes in surrounding light and noise. With the onset of darkness, the pineal gland in the brain starts to secrete melatonin, known as the "hormone of darkness." Melatonin helps the body fall asleep and stay asleep, but it is not strong enough to do so on its own.
>To sleep well during a flight, it is important to avoid excessive consumption of caffeine and alcohol. Caffeine may prevent you from falling asleep, and alcohol will prevent you from staying asleep and experiencing normal restorative stages of sleep. The use of earplugs and an eye mask to reduce noise and mimic darkness may also help.If these measures are not sufficient, try taking between 0.3 mg and 1.0 mg of melatonin 30 minutes before your bedtime. Upon arrival at your destination, stay active during daylight hours, and go to bed in the evening at your usual time. You might also consider taking melatonin before your bedtime for the ?rst few days at your destination. In the morning, going out in the sunlight will help your circadian rhythm adjust. If weather prohibits exposure to sunshine or if you are traveling from a summer climate to a winter one, try to start your morning with exercise at a gym or swimming pool.About Melatonin
>Classifed as a food supplement, melatonin is available without a prescription and is not regulated by the U.S. Food and Drug Administration (FDA). The amount of active hormone in one dose may vary slightly from what is declared on the box, and response to melatonin varies individually. Excessive melatonin may interfere with your sleep. Avoid taking more than 3.0 mg at once, as too much melatonin can cause headaches, nausea, dizziness or irritability.
>Considered nonaddictive and safe for short-term use, melatonin can interact with certain medications, however, including anticoagulants, immune suppressants, diabetes medications and birth-control pills. If you have any health conditions, check with your doctor before using melatonin.
>Refrain from activities that require alertness — such as driving, boating or diving — for four to five hours after taking melatonin.
>Observe members of a boat crew for evidence of drowsiness and jet lag, as its effects will be cumulative if not addressed. Just one crew member's impairment can result in increased burdens and fatigue on a small crew. If the conditions are left undetected, an impaired watchstander can have catastrophic consequences for the boat.