Jet lag, also known as “time zone change syndrome,” is not a problem due to lack of sleep. It is a condition that actually results from an imbalance in the body’s natural “biological clock” caused by traveling to different time zones, according to the National Sleep Foundation.
The 24-hour cycle, called the circadian rhythm, is measured by the rise and fall of body temperature, plasma levels of certain hormones – all influenced by what we do and when. It adjusts slowly when people travel to different time zones, resulting in feeling sleepy in the afternoon and staying awake in the middle of the night.
Waking patterns, eating habits, meal times, and sunlight will all affect whether it takes a person a few days or, in extreme cases, weeks to get over jet lag. An altered sleep pattern is just one common side effect. Other possible symptoms include fatigue, indigestion, muscle soreness, headaches, lack of focus, and irritability.
Flying eastward is problematic because you’ll need to fall asleep when your body thinks it’s still early afternoon. You have to seek out light in the morning and avoid it at night. The opposite is true if you’re flying west. Traveling south, for example, shouldn’t result in a bad case of jet lag because you’re probably staying in the same time zone.