Jet-lag is a sleep disorder that affects those who travel by crossing at least 3-4 time zones, either westward or eastward, due mainly to the temporary failure of synchronization between the internal biological clock (circadian rhythm) and changes in ambient light at different times of the day.
By its very nature, jet lag is a transient discomfort that does not have a significant impact on overall health and tends to spontaneously subside over a few days as the biological clock reprograms itself, aligning with the schedules and light-dark alternation of the destination.
This does not detract from the fact that, if you are taking business or leisure trips of only a few days’ duration, suffering from jet-lag may compromise the purposes of the trip or otherwise make the experience far from pleasant.
A disorder similar to jet-lag affects workers who must perform their duties on shifts that involve all or part of the night hours.
In these cases, for reasons intrinsic to the need to stay unnaturally awake during the night and sleep during the day, the alteration in sleep-wake rhythm is more difficult to manage and, over time, can have considerable psychophysical repercussions, increasing the risk of developing cardiovascular diseases (starting with hypertension), digestive disorders, altered appetite and metabolism, endocrine dysfunction, reduced fertility, and psychiatric disorders.