What Is Jet Lag?

Jet lag is a temporary sleep disorder that occurs when your internal body clock (circadian rhythm) is out of sync with the local time at your destination. It is caused by rapid travel across multiple time zones, most commonly on long-haul flights. Symptoms include difficulty falling asleep or staying asleep, daytime fatigue, difficulty concentrating, irritability, and digestive discomfort.

Your body clock is primarily regulated by light exposure, meal timing, and physical activity. When you arrive in a new time zone, your brain still expects the light and dark cycle of your departure city. Until it adjusts, you experience jet lag.

How the Jet Lag Sleep Planner Works

This tool calculates the time zone difference between your origin and destination, determines whether you need to shift your body clock earlier or later, and generates a day-by-day adjustment plan. It considers your normal sleep schedule, trip length, travel direction, and flight timing to produce practical advice on when to sleep, seek sunlight, limit caffeine, and take short naps.

For short trips of 1 to 3 days, the planner may recommend partially staying on your home schedule to avoid the disruption of adjusting twice. For longer trips, it focuses on shifting your body clock to match destination time as quickly as possible.

Eastbound vs Westbound Jet Lag

Most travellers find eastbound travel harder to adjust to than westbound. When flying east, you need to fall asleep earlier than your body expects, which is more difficult than staying up later. When flying west, you simply stay awake longer, which most people can do naturally.

As a general rule, your body can adjust by about one hour per day when flying west and about 45 minutes per day when flying east. A six-hour eastbound shift may take a full week to recover from without a structured plan.

When Should You Sleep on a Long Flight?

If you are on an overnight flight heading east, try to sleep during the first half of the flight when it is still night at your origin. If you are on a day flight heading west, stay awake as long as possible to align with your destination evening. On mixed or connecting flights, aim to sleep when it is nighttime at your destination, even if you do not feel tired yet.

Avoid relying on alcohol to fall asleep on flights. It disrupts sleep quality and increases dehydration. Earplugs, an eye mask, and a neck pillow are far more effective.

Should You Nap After Arrival?

Short naps of 20 to 25 minutes can help reduce fatigue without interfering with your ability to fall asleep at the correct local time. Longer naps, especially those exceeding 90 minutes, can delay your adjustment by reinforcing your home time zone schedule. If you arrive in the morning or afternoon, resist the urge to sleep until at least 8 PM local time.

Best Jet Lag Tips for International Travel

• Start shifting your sleep schedule 2 to 3 days before departure.
• Get bright sunlight at strategic times based on your travel direction.
• Avoid caffeine within 6 hours of your target bedtime.
• Eat meals on destination time as soon as you board.
• Stay hydrated throughout the flight and after arrival.
• Exercise lightly in the morning at your destination to signal wakefulness.
• Avoid screens in bed on your first night at the destination.
• If you must nap, set an alarm for 25 minutes.

Jet Lag Sleep Planner FAQ