What should you know about jet lag time?

After a flight across time zones, your internal signals for sleep, alertness, hunger and digestion may arrive at the wrong local hours. You may feel awake when the destination expects sleep, then become sleepy during the day. Difficulty sleeping, headache, irritability and poor concentration can accompany this shift.

The clock is influenced by light, activity and meals, so staying on the old schedule can prolong the mismatch. Jet lag is not the same as simply feeling tired after a journey; persistent or severe symptoms may have another cause.

Change your watch and routine to local time on arrival. Wake, eat and go to bed according to the destination schedule, and use daylight strategically during the day. Keep evening surroundings dim and the bedroom dark, quiet and cool. Gentle activity can help you stay awake until a reasonable local bedtime.

If you nap, choose a brief nap earlier in the day. Drink water and avoid alcohol as a sleep strategy. Caffeine may help alertness but can interfere with bedtime when taken late. Ask a clinician or pharmacist before using melatonin, antihistamines or other sleep medicines, particularly if you have a medical condition or take regular medication.

Get urgent care for chest pain, severe breathlessness, collapse, sudden weakness, confusion, or a sudden severe headache. Seek medical advice if you remain unable to sleep, are dangerously sleepy during normal activities, cannot keep fluids down, or develop fever or significant pain. A travel health consultation can be useful before future complex itineraries.

Which local-time cues should I use for this journey? Should I adjust my schedule before flying home? Is a sleep aid appropriate with my health conditions? How can I tell jet lag from insomnia or another illness?