Some people are more susceptible to jet lag than others. The primary symptom of jet lag is extreme fatigue. In fact, you may be so sleepy that you almost feel sick. You may also experience the following:

• Anxiety
• Cardiac arrhythmias (on rare occasion)
• Confusion
• Digestive upsets that may include constipation, diarrhea, or a combination of both
• Headache
• Insomnia
• Irritability
• Lowered immunity to illness
• Memory loss
• Nausea
• Poor muscular coordination
• Profuse sweating

These symptoms aren't exactly the sort of companion you want along on your dream trip. The good news is that jet lag is self-limiting and doesn't have any long-term detrimental effects. The bad news is that while you have it, you feel so lousy that it may spoil your trip, or diminish your effectiveness if you're on a business trip and expected to be sharp.