Jet Lag is classified as a secondary circadian dysrhythmia and as a circadian rhythm sleep disorder.
Jet lag occurs with rapid travel across time zones, resulting in a misalignment between the timing of body's circadian rhythms with those of the external physical environment. Symptoms include general malaise, daytime sleepiness, difficulties in initiating or maintaining sleep (i.e. insomnia), impaired performance, and decrements in subjective daytime alertness and performance. These symptoms usually last for several days until the traveler adapts to the new time zone. Some people also notice digestive and bowel movement problems. An article published in the journal Lancet said "More than 20 studies investigated the effect of constant light, dim light at night, simulated chronic jet lag, or circadian timing of carcinogens, and most showed a major increase in tumour incidence."
Senior citizens generally need longer to recover from jet lag. Their circadian cycles are slower to adjust to the new time zone.
Eastward travel (requiring advancing circadian rhythms and sleep-wake hours) is usually more difficult to adjust than westward travel. Eastward travel generally results in difficulty falling asleep and westward travel in difficulty maintaining sleep. Jet lag can also be made worse by poor air quality (in the plane and after the flight) and being forced to sit still for a long flight.
While getting rid of jet lag will take some time, there are some ways that you can reduce its troublesome symptoms.
Make sure that everything in your life is in order – in other words, make sure you don't spend the travel time worrying about anything. Try not to fly tired, hung over, or sick.
Make sure you dress comfortably for the flight, and bring soft slippers with you so you can take off your shoes. Also bring blindfolds, neckrests, or earplugs – anything to help you sleep. Try not to sit still for too long – periodically walk the aisles, and do some stretching exercises in your seat to avoid blood clots.
When your plane stops over somewhere take the opportunity to deplane. If there's an opportunity to get a shower at the stopover point, then by all means do so. It'll be good to stretch your legs before another grueling flight, and a shower will make you feel even better.
Many people make the mistake of getting a full eight hours of sleep immediately upon arriving at their destination. This makes it harder to adjust your body clock to the current time zone. If you really have to sleep, take only two hours to get rid of the worst fatigue. After waking up, take an hour's walk in the sun to help your body get used to the change.
There's a rule of thumb that the best way to get rid of jet lag is gradually over a few days. The number of days should be according to the number of time zones crossed. In other words, you'll need to adjust your body clock by one or two hours every day.
Certain medications can help you sleep earlier, but remember to only
use these as a last resort – they may make jet lag worse.
You pretty much have to plow through it. Exposure to daylight at your new location can help reset your circadian clock, and it is a good idea to take a walk right after you wake up. Physical factors (mostly outdoor lighting, and to a lesser extent temperature changes) and social factors (what everyone else is doing), help you get in alignment with your current time zone after trans-meridian travel.
Remember to follow the normal rules for getting good sleep: no long naps at the wrong time, good hygiene, watch the caffeine and alcohol. A recent report from Japan’s Nagoya University's Institute of Transformative Bio-Molecules says the newly developed protein KL001 can affect the circadian cycle and may be lead to a treatment for jet lag. Animal tests are planned. This protein or a mix of this and other proteins is said to affect the CRY protein, one of the four master proteins that seem to be critical in the body clock.
A 2003 article in the Cornell Hotel and Restaurant Administration Quarterly recommends hotels serving international travelers take measures to help their guests recover from jet lag. These include measures to get the traveler’s circadian rhythm adjusted to local time and a good sleep during nighttime at the hotel. Measures include commonsense things like a comfortable mattress and temperature control, as well as the ability to produce total darkness in the room. The hotel should also provide opportunities to easily experience bright sunshine as this is an effective way to reset the circadian clock.
Social jet lag is the disconnect between biological time and social time. It’s easily seen in night owls expected to get to the office early. People with advanced sleep phase disorder or delayed sleep phase disorder feel out of sorts when restricted by social convention to be alert at the “wrong” time for them and consequently have symptoms like those of jet lag. Daylight Savings Time makes social jet lag worse for a lot of people.