Cause

• After vacationing in a different time zone, jet lag is caused by the body clock of an individual adjusting slowly to a return to its original time zone. The CDC reports that the body has an internal rhythm helping us know when to sleep that is knocked out of synchronization with its environment by long-distance travel.
  
  

Symptoms

• The Mayo Clinic details the symptoms of jet lag as including problems sleeping, either from early waking or trouble getting to sleep. Other symptoms can include daytime fatigue, constipation or diarrhea and muscle soreness.
  
  

Time Zones

• Jet lag usually occurs after one or two days of travel and it takes approximately one day per time zone crossed to recover from the effects, according to the Mayo Clinic. Jet lag is not usually a problem following a vacation in the same time zone as an individual's usual residence.
  
  

Direction

• According to the CDC, the direction traveled during air travel can have an effect on the severity and symptoms of jet lag suffered. Eastward travel is said to present more problems and is associated with difficulty falling asleep at night and waking up, while westward travel usually causes sleepiness in the early evening and early awakening.
  
  

Treatment

• The CDC explains that treatments for jet lag following a vacation are used rarely as the condition is temporary. However, the Mayo Clinic reports medications such as benzodiazepines are used to help a patient sleep during a flight and in the days following a vacation. A more commonly used treatment is light therapy, which simulates sunlight with artificial light to bring the body clock back to its prevacation rhythm.