Jet lag is a physiological condition that disrupts our body's circadian rhythm. It is therefore classified as a circadian rhythm disorder. Jet lag is also known as time zone change syndrome or desynchronosis. It occurs when you travel rapidly from east to west, or west to east in an aircraft.

People suffering with jet lag tend to feel drowsy, tired, irritable, lethargic, and slightly disoriented. The more time zones that are crossed rapidly, the more severe the jet lag symptoms are likely to be.  Jet lag symptoms generally are harsher and will last longer the older you are. A child's symptoms will usually be much milder, and they will recover faster.

Until the body’s circadian rhythm readjusts properly to our new environment, we are jet-lagged.

A good night's sleep helps recover from jet lag more quickly. The severity and symptoms of jet lag vary and depend on several factors, including how many time zones were travelled, age, state of health, how much was eaten during the flight, and how much sleep there was during the flight.

Jet lag symptoms may include:

  • Disturbed sleep — such as insomnia, early waking or excessive sleepiness
  • Daytime fatigue
  • Difficulty concentrating or functioning at your usual level
  • Stomach problems, constipation or diarrhea
  • A general feeling of not being well
  • Mood changes

Jet lag symptoms usually occur within a day or two of travel if you've travelled across at least two time zones. Symptoms are likely to be worse or last longer the more time zones that you've crossed, especially if you travel in an easterly direction. It usually takes about a day to recover for each time zone crossed.

There are a number of things to do to minimize the symptoms of jet lag:

  • People who are physically fit, rest properly, and eat a well-balanced diet tend to have fewer and lighter symptoms of jet lag than other individuals.
  • Drinking plenty of liquids during the flight - preferably water and definitely not alcohol or caffeinated drinks - will help reduce symptoms.
  • Get a sufficient amount of sleep as soon as you can to sync up with your new time zone. Adapt to local timetables immediately; this will speed up the body clock's adaptation to a new environment.