Jet Lag
Also known as: Circadian rhythm disruption, Time zone fatigue, Desynchronosis
Jet lag is a temporary sleep disorder caused by crossing multiple time zones faster than your body can adjust.
Last updated: 2 April 2026
Real-world example
You fly from London to Tokyo (9 hours ahead). You arrive at 10am local time but your body thinks it's 1am. You're exhausted but force yourself to stay awake until 9pm. By day 3 you're mostly adjusted. Your colleague who napped until 4pm on arrival is still waking at 3am a week later.
Why travellers need to know
Jet lag affects decision-making, reaction times, and immune function. For travellers managing chronic conditions, it also disrupts medication schedules. Eastward travel is harder than westward because compressing your day is more difficult than extending it. A general rule: it takes roughly one day per time zone crossed to fully adjust. Melatonin, light exposure timing, and strategic caffeine use all help.
Country-specific notes
Melatonin available OTC at pharmacies and convenience stores
Japan sells melatonin as a supplement without prescription. You can find it at most pharmacies and some convenience stores, making it easy to manage jet lag on arrival from Europe or the Americas.
Frequently asked questions
How Nomedic helps
Nomedic stores your medication schedule so you and your doctor can plan timing adjustments for long-haul travel.
Your health records, anywhere you go
Your medication schedule, adjusted for every time zone.
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