Jet lag occurs when we travel between time zones, disrupting our circadian rhythm. The primary symptoms include fatigue, difficulty concentrating, stomach problems, mild sickness, and trouble falling asleep in the evening.

The circadian rhythm, or the body clock, operates on a roughly 24-hour schedule and affects many aspects of our body. These include hunger, digestion, body temperature, hormones, and urine production. However, our body clock’s most significant impact is regarding our sleep schedule.

When it gets dark, we start to get sleepy, and in the same way, we find it easier to wake up once the sun has risen. Our body clock is, therefore, affected by brightness. Even so, these adjustments take time, so when travelling between time zones, our body clock will remain the same despite external conditions changing. Our body clock is no longer in sync with the local time.

Jet lag is a temporary state. Typically, it takes our body one day to recover for every time zone passed. For example, if we fly from New York to London (4-hour difference), it will take us about four days to recover. The severity of the jet lag depends on how many time zones were passed and in which direction. It is easier to adjust when flying from the east to the west (going back a few time zones), as staying up longer comes more naturally for us than going too early to sleep.

For most people, jet lag is nothing of concern. Nevertheless, for people who fly very regularly, such as pilots and flight attendants, jet lag can cause problems. Older adults are also more likely to have severe jet lag.

To reduce the symptoms, it is recommended to minimize caffeine- and alcohol consumption, spend time outdoors, exercise, and eat and drink in accordance with the current local time. Melatonin intake can also be helpful but should only be carried out under the supervision of a doctor.

References and further information can be found on the American Academy of Sleep Medicine’s website: