Jet lag: understanding and adapting to the world clock

The world is divided into 24 time zones, each set according to the position of the sun relative to the Earth. This means that when it is noon in Paris, it is midnight in Los Angeles and 7 p.m. in Beijing. This phenomenon, called jet lag , is an unavoidable reality for travelers, professionals working internationally and even top athletes.

But beyond a simple time change, jet lag profoundly influences our body, our productivity and even our mood. How does it work exactly? What are its effects and how can we adapt to it effectively? Let's dive into the fascinating world of time and its variations.

1. Understanding jet lag

Jet lag is a direct consequence of the time zone system. To understand it better, let's go back to basics.

1.1. Why time zones?

The Earth rotates on its axis every 24 hours, gradually exposing different parts of the globe to sunlight. To harmonize time across the world, the planet has been divided into 24 time zones , each one corresponding to an hour's difference from the previous one.

Coordinated Universal Time (UTC) serves as a reference for all time zones. Thus:

• London (United Kingdom) is at UTC+0
• Paris (France) is UTC+1 in winter, UTC+2 in summer
• New York (USA) is UTC-5 in winter, UTC-4 in summer
• Beijing (China) is UTC+8 all year round

When you travel quickly from one time zone to another, your body clock doesn't adjust instantly. That's when jet lag begins.

2. What are the effects of jet lag?

Jet lag isn't just a clock issue. It profoundly affects our circadian rhythm , our internal biological clock, which regulates our sleep, appetite, and energy.

2.1. Fatigue and drowsiness

When you travel across time zones, your body stays in sync with the time at your starting point. As a result, you feel sleepy during the day and wake up in the middle of the night.

For example, if you fly from Paris (UTC+1) to New York (UTC-5), your body still thinks it's six hours later . At 6pm in New York, it will be midnight for your body and you will have a hard time staying awake.

2.2. Sleep disorders

One of the most common effects of jet lag is insomnia. Depending on the direction of travel, you may fall asleep too early or have trouble falling asleep. It often takes your body several days to adjust.

2.3. Digestive disorders

Jet lag also disrupts your appetite. You may suddenly feel hungry in the middle of the night or, conversely, have no appetite at local meal times.

2.4. Decreased concentration and performance

Students, professionals and athletes on the move face decreased concentration and physical performance due to jet lag.

3. Why does the direction of travel play a role?

The direction you travel affects the severity of jet lag.

3.1. Journey to the West (example: Paris → New York)

Traveling west is generally less disruptive because the day is longer. Your body adjusts more easily to a later night.

3.2. Traveling East (example: Paris → Tokyo)

Traveling east is more difficult because the days are shorter. You have to go to bed earlier than usual, which puts more strain on your internal clock.

4. How long does it take to adapt?

The adaptation time depends on the number of time zones crossed. It is generally considered that:

• It takes about a day per time zone crossed to fully recover.
• If you travel across three time zones , it will take you three days to adjust.
• Young people adapt more quickly than older people.

5. How to minimize the effects of jet lag?

Fortunately, there are several strategies to help alleviate jet lag.

5.1. Before the trip

• Adjust your sleep schedule gradually : If you're traveling east, try going to bed earlier a few days before departure. If you're traveling west, go to bed later.
• Hydrate well : avoid alcohol and caffeine, which disrupt sleep.
• Rest before departure : do not leave without sleeping, this would aggravate the effects of jet lag.

5.2. During the flight

• Set your watch to the time of the destination country upon boarding .
• Try to sleep if you arrive in the morning and stay awake if you arrive in the evening.
• Expose yourself to natural light during the flight to help your body adjust.

5.3. After arrival

• Spend time outdoors : Sunlight is the best way to recalibrate your body clock.
• Eat at local times even if you are not hungry.
• Avoid long naps : If you are tired, a 20-minute nap is enough.

6. Jet lag and technology

With globalization, jet lag has become a major concern for businesses and travelers. Fortunately, there are several applications that help you manage it better:

• Timeshifter : Offers personalized plans to accommodate jet lag.
• Jet Lag Rooster : Calculates optimal sleep schedules to minimize the effects of jet lag.
• F.lux and Night Shift : adjust the light from screens to make it easier to fall asleep.

7. Special cases: countries with a single time zone

Some countries, although very large, only use one time zone:

• China (UTC+8) : Although the country covers 5 natural time zones, the entire country operates on Beijing Time.
• India (UTC+5:30) : The entire country has a single time, despite its large area.
• Russia : Conversely, this country has retained 11 time zones to better reflect its geography.

Conclusion: A global challenge, but manageable

Jet lag is an unavoidable phenomenon in our connected world, but it can be managed with a few precautions. Whether you’re a casual traveler or a globetrotter, understanding how your body reacts to jet lag will help you better adjust and enjoy your travels to the fullest.

Next time you travel far, apply these tips and you'll arrive at your destination in great shape!