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Redwood Falls Gazette
  • Dr. Jeff Hersh: Calibrating your circadian rhythm

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  • Q: Why do people get jet lag?
    A: There are many hormones (from the brain, adrenal glands, liver, pancreas and many other organs) whose levels vary throughout the day, regulating many body functions and defining our circadian rhythm (how our body adjusts to the 24-hour cycle dictated by the earth’s rotation). Plants and animals also have circadian rhythm. If the length of a day on earth changed, life on earth would need to adapt; if we migrated to another planet we would presumably need to adapt to the length of a day on that planet.
    The day/night (light/dark) signals we receive from sunlight help calibrate our circadian rhythm. Therefore, when the light/dark cycle is compromised, for example close to the poles where day is mostly sunlight in the summer but little sunlight in the winter, people’s circadian rhythm may be disrupted; in these cases light therapy treatment (using manmade light to define “day” and “night”) may be beneficial. Other examples where normal circadian rhythm may be compromised include night shift work (requiring people to “counter-adjust” to the light/dark cycle), and travel across time zones (where a “day” effectively becomes more or less than 24 hours) commonly called jet lag.
    When someone travels across two or more time zones, changing the length of their “day” by two hours or more, their circadian rhythm, and in particular their sleep pattern, is abruptly disrupted. One of the main hormones that regulates our daily sleep pattern is melatonin, secreted by the pineal gland in the brain; it has very low levels during the day, increasing in the evening.
    Jet lag often causes difficulty falling and/or staying asleep. This may cause daytime drowsiness, possibly leading to difficulty concentrating, mood changes, decreased mental acuity and/or decreased memory. Other symptoms may include gastrointestinal upset (such as nausea, changes in bowel movements, abdominal discomfort), fatigue, muscle aches, headaches and/or malaise.
    Most travelers that cross two or more time zones experience at least some jet lag symptoms. These are generally more pronounced when more time zones are crossed and for eastward travel (where ‘time is lost’).
    There are many things that can be done to help minimize the effects of jet lag. Prior to starting travel:
    * Maximize sleep so you are not “sleep deprived” when you start your trip.
    * For eastward travel, start to go to bed earlier (and wake up earlier, still ensuring you get a full night’s sleep) for at least several nights before your trip; for westward travel stay up/wake up later for several days prior to travel.
    While on the plane:
    * Stay well hydrated. Avoid alcohol and caffeine, both of which may affect sleep patterns.
    * Start following your destination sleep times; this may mean staying awake (westbound) or trying to sleep (eastbound) on the plane.
    Page 2 of 2 - On arrival:
    * Adjust your sleeping, eating, exercise, etc. to the local time.
    * Get exposure to local sunlight.
    * Ensure your sleep environment is conducive to sleep.
    Other considerations:
    * Since traveling can be tiring, pick a flight that arrives during local evening time.
    * Arrive early to get over your jet lag; as a rule of thumb it will take one day for every two time zones crossed to completely adjust, although this varies quite a bit from person to person and situation to situation.
    * As noted above, melatonin helps regulate sleep. It is sold over-the-counter as a dietary supplement. It may be taken (the best dose has NOT been established, but some evidence suggests up to 5 milligrams may be an appropriate adult dose) 30 minutes before bedtime (defined by the destination time) on the evening of departure for eastbound and the evening of arrival for westbound travel, and then nightly for three to four days. Some people may develop side effects to melatonin of daytime sleepiness, disorientation, nausea or others, and melatonin may interact with other medications (for example warfarin), so consultation with your healthcare provider is needed before using this medication.
    * Although sleep medication may help some people, for some it may make jet lag adjustment harder; these medications should only be taken under the guidance of your healthcare provider.
    * Business travelers who are going for a very short time may try to keep on their origin location time schedule, “popping” in for their meeting(s) and returning home. They need to consider the time of their meetings with regard to their origin location time, since if the destination time of the meeting corresponds to 3 a.m. in their origin time they may not “be at their best” with this strategy.
    ——
    Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.

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