Fatigue

• Fatigue is the most common symptom of jet lag. Your sleeping patterns have been thrown off, and your biological clock is not in sync with the clocks in the new time zone. Dehydration from time spent in the dry air of the plane can add to this feeling.
  
  

Insomnia

• Ironically, even though you may be tired, you also may have trouble sleeping. If you go to sleep at your normal bedtime of 10 p.m., for example, your body still thinks it's early. Also, many people use caffeine to stay awake during the day, which can interfere with getting to sleep at night.
  
  

Hunger or Loss of Appetite

• Mealtimes are also thrown off when you have jet lag, so you may find yourself feeling hungry at your "normal" lunchtime rather than lunchtime in your current time zone. At the same time, you may have no appetite when you sit down for dinner.
  
  

Stomach Problems

• The changes in time zone that affect your sleeping and eating patterns can also affect your bowel movements. Constipation and diarrhea are both common symptoms of jet lag.
  
  

Irritability

• Tiredness, hunger and bowel issues often combine to create feelings of irritability or even anxiety. Fortunately, all of the symptoms should abate in a few days, depending on how many time zones have been crossed.