Jet Lag: Causes, Symptoms, and Natural Solutions

Jet lag, or time zone change syndrome, is far more than simple travel fatigue. It's a profound desynchronisation between your internal biological clock and local destination time — with real consequences for sleep, digestion, cognitive performance, and even the immune system.

What exactly is jet lag?

Your biological clock is synchronised to a 24-hour rhythm (circadian rhythm), primarily regulated by light. When you cross multiple time zones in a few hours, your internal clock remains set to your departure time while the external environment runs on a different schedule. This time zone change creates a conflict that takes the body time to resolve.

As a general rule, spontaneous recovery takes about one day per time zone crossed. A flight from New York to Tokyo (14 hours of difference) theoretically requires 14 days of complete recovery without active strategy.

East vs west: very different impacts

Travelling east (advancing the clock) is harder than travelling west (putting the clock back). Our biological clock naturally runs on a rhythm slightly longer than 24 hours — so it's easier for it to lengthen the day than to shorten it. Insomnia after an eastbound transatlantic flight (Paris → New York on the return journey) is therefore more frequent and more severe.

Jet lag symptoms

• Nighttime insomnia or excessive daytime sleepiness
• Difficulty concentrating and cognitive slowdown
• Digestive disturbances (the microbiome also has its own circadian clock)
• Irritability and mood swings
• Headaches and loss of appetite

Natural solutions for recovering from jet lag

Before the trip: gradually shift your bedtime 2 to 3 days before departure — earlier if travelling east, later if heading west. Stay well hydrated in the 24 hours beforehand.

On the plane: immediately set your watch to the arrival time and mentally adopt that rhythm. Avoid alcohol and caffeine. If travelling east, try to sleep during the flight — a blackout sleep mask creates the darkness needed to signal to the brain that it's time to sleep, even at 35,000 feet.

On arrival: immediately expose yourself to natural light according to local time — it's the most powerful signal for resynchronising the biological clock. Resist a long nap if it's still daytime. Adopt meal times on the local schedule. Melatonin (0.5 to 5mg) taken at local bedtime can accelerate resynchronisation.

The following nights: maintain complete darkness to avoid disrupting melatonin. Mulberry silk, a naturally thermoregulating material, helps stabilise body temperature — a key factor in sleep quality during a period of circadian adaptation.

On the flight itself, darkness is the only circadian signal you actually control. A blackout silk mask tells the brain it is night at ten thousand metres, and the first day of recovery mostly depends on that.