Jet Lag: Causes, Symptoms, and Natural Solutions

Jet lag, or time zone change syndrome, is much more than just travel fatigue. It's a deep desynchronization between your internal biological clock and the 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 synchronized to a 24-hour rhythm (circadian rhythm), primarily regulated by light. When you cross several time zones in a few hours, your internal clock remains set to your original time while the external environment operates on a different time. This time difference creates a conflict that the body takes time to resolve.

As a general rule, spontaneous recovery takes about 1 day per time zone crossed. A flight from Paris to Tokyo (an 8-hour time difference) theoretically implies 8 days of full recovery without an active strategy.

East or West: Very Different Impacts

Travel to the east (moving time forward) is more difficult than travel to the west (moving time back). Our biological clock naturally has a rhythm slightly longer than 24 hours, so it's easier for it to extend the day than to shorten it. Insomnia after a transatlantic flight eastward (New York → Paris on return) is therefore more frequent and severe.

Symptoms of jet lag

• Nocturnal insomnia in the evening or excessive daytime sleepiness
• Difficulty concentrating and cognitive slowdown
• Digestive problems (the microbiota also has its circadian clock)
• Irritability and mood swings
• Headaches and lack of appetite

Natural solutions for recovering from jet lag

Before travel: Gradually shift your bedtime 2 to 3 days before departure, earlier if traveling east, later if traveling west. Hydrate thoroughly in the 24 hours prior.

On the plane: Immediately synchronize your watch to the arrival time and mentally adopt this rhythm. Avoid alcohol and caffeine. If traveling east, try to sleep during the flight; an opaque sleep mask creates the darkness needed to signal to the brain that it's time to sleep, even at 30,000 feet.

Upon arrival: Immediately expose yourself to natural light according to local time; this is the most powerful signal for resynchronizing the biological clock. Resist prolonged napping if it's still daytime. Eat meals at local times. Melatonin (0.5 to 5 mg) taken at local bedtime can accelerate resynchronization.

Subsequent nights: Maintain complete darkness to avoid disrupting melatonin. Mulberry silk, a natural thermoregulating material, helps stabilize body temperature, a key factor in sleep quality during circadian adaptation.