What should you know about fighting jet lag?

Jet lag occurs when your internal sleep-wake rhythm is out of step with the local clock after crossing time zones. You may have difficulty sleeping at the expected time, daytime sleepiness, headache, poor concentration, or changes in appetite and mood. The adjustment is influenced by travel direction, the number of time zones crossed, light exposure, sleep loss, and your usual routine. Symptoms are not a diagnosis of another illness, but a different problem may need attention if they persist.

Before departure, protect your sleep and consider moving bedtime and meals closer to the destination schedule when practical. On the flight, drink water, limit alcohol, move your legs, and sleep only when it fits the planned adjustment. After landing, use daylight during the local day, keep naps short or avoid them if they delay bedtime, and eat on local time. Keep important decisions and strenuous tasks flexible while sleepy. A travel-health consultation can help if you take regular medicines, have a chronic condition, or need advice about sleep aids.

Contact a clinician if symptoms do not begin settling after your body has had time to adjust, or if sleep disruption is severe, recurrent, or affecting work and driving. Seek urgent help for chest pain, severe breathlessness, fainting, sudden confusion, or a severe unusual headache with neurological symptoms.

Ask how to time light and sleep for your route, whether a medicine or sleep aid is appropriate for you, how to protect a chronic condition during travel, and when it is safe to resume demanding activities.