According to the American Sleep Association Jet lag is “is a physiological condition caused by disturbance to the body’s natural circadian rhythm, or internal clock”. It’s something most people have experienced when the travel, being from the west coast I can vouch that the three hour time difference from here to California always messes me up for a good three days until I become used to the different time zone. What I thought was interesting was that here on the east coast I tend to sleep around 1 am and wake up around 9am the next morning, making it 11 pm and 7 am back home on the west coast, but when I would fly between I would still feel the disruption.
The “circadian rhythm” is the “natural tendency of living things” and is that all living things are based around a 24 hour cycle, which influenced largely by the cycles of sun and darkness, day and night. When your cycle is disrupted by changing environments, you can experience an “adverse and conflicting biological and brain wave activity as [your body] attempt to cope to the new cycle”, which results in the symptoms of jetlag such as fatigue and irritability. Bright lights are the “most powerful” way to cause a phase shift, or an advacement or delay in circadian rhythms. Where bright light comes from waking in the morning “makes you wake up earlier” or “phase advance” and where light around the time you sleep, “makes you wake up later” which is known as “phase delay”.
According to the ASA “west to east [coast] travel is considered the more adverse than vise versa, [because] it pushes the cycle forward rather than back”. Although it is important to note that Jet lag affects each person differently, where some experience it for only a day between time zones, where other can have a more severe case. “Whether circadian rhythms align with the environment is determined by factors such as exercise, melatonin, and light,” says the Scientific American.
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A study conducted by Helen Burgess of the Rush University Medical Center in Chicago, looked at how to prevent jet lag by departing before phase shifting or leaving for another time zone before you shift in your cycle. The findings of the observational study where that “After three days of light exposure in the morning, the participants’ circadian rhythms shifted by an average of 2.1 hours”. This means that they would be adjusted to the time zones well by two days earlier than predicted, because they were “seeking and avoiding light at the right times” which allowed them to reduce their jet lag as they moved between time zones.
There have been other studies tested ways to cope with jet lag with different variables such as the use of melatonin to judge the change those variables had on the sleep patterns of those traveling between zones. One study called “How to Trick Mother Nature into Letting You Fly Around or Stay Up All Night”, explored the usage of melatonin and found that “taking 5 mg melatonin at local bedtime for 4 days after the flight”, and that later “A review of 10 years of studies showed an overall 50% reduction in subjective assessment of jet lag symptoms with melatonin”. Jet lag is a natural and inconvenient reaction your body has when you change between time zones, it’s healthy to sleep but it is also beneficial to plan ahead of time when you are switching between zones, so the the use of melatonin or adjusting your sleeping schedule before is helpful to combat nasty jet lag.
Work Cited
http://www.sleepassociation.org/patients-general-public/jet-lag-2/
http://www.ncbi.nlm.nih.gov/pubmed/12076414
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3841977/
http://www.scientificamerican.com/article/how-to-prevent-jet-lag/