Jet lag happens when your internal body clock has not yet caught up with the local time at your destination. A common rule of thumb is that your circadian rhythm resets at roughly one hour per day — for a 6-hour time difference, that is about 4 to 5 days westbound and 6 to 7 days eastbound. Eastbound travel (losing hours) tends to feel harder than westbound travel (gaining hours). The table below breaks the estimates down by hours of time difference.
This guide walks through what you can do before you leave, and four habits that help your body clock catch up after you arrive.
Why jet lag happens
Your body clock runs on a cycle close to 24 hours. It uses cues like morning light, meal timing, and activity to stay aligned with the outside world. When you fly across several time zones, your clock is still running on your home schedule while the world around you is on local time. That mismatch shows up as poor sleep, daytime sleepiness, appetite changes, and reduced focus.
The mismatch also shifts where your individual sleep cycles land within the night. The first cycle of the night may start at the "wrong" body-clock time, which makes deep sleep and REM less reliable for several days. If you want background on how those cycles work, Sleep Cycles Explained walks through the 80–110 minute loop and why total sleep often matters more than hitting an exact boundary.
To close the gap, you need to give your body new cues — light, food, and sleep — on the new schedule.
Common symptoms of jet lag
Jet lag shows up differently for different people, but the most common signs include:
- Disrupted sleep — trouble falling asleep at night, or waking too early in the local morning
- Strong daytime sleepiness and reduced focus
- Appetite changes and mild digestive issues (upset stomach, irregular bowel movements)
- Mild low mood or irritability
- Headache
Disrupted sleep tends to be strongest on the first local night — eastbound trips usually show up as trouble falling asleep, while westbound trips show up as waking too early. Older travelers, people who already have sleep problems like insomnia, and those who cross time zones frequently in short succession tend to feel symptoms more strongly. Because strong daytime sleepiness lowers attention, it is safer to go easy on driving and important decisions on your first day.
Symptoms tend to appear after crossing roughly two or more time zones, and eastbound trips usually feel harder than westbound. As a general guidance, the body clock shifts at about one hour per day, so a longer time difference means a longer recovery.
How long jet lag usually lasts (by time difference)
A common rule of thumb is that your body clock adjusts at roughly one hour per day. Eastbound trips (losing hours) tend to take longer to recover from than westbound trips (gaining hours). The table below sketches typical recovery windows by time difference.
| Time difference | Westbound (rough estimate) | Eastbound (rough estimate) |
|---|---|---|
| 4 hours | About 3–4 days | About 4–5 days |
| 6 hours | About 4–5 days | About 6–7 days |
| 9 hours | About 7–9 days | About 9–12 days |
| 12 hours | About 8–10 days | About 10–14 days |
These are general estimates. Your actual recovery varies with age, baseline sleep quality, and the demands of the trip. On short trips you may head home before jet lag fully resolves; in that case, "minimizing daytime sleepiness and nighttime insomnia" is often a more practical goal than fully resetting your body clock. The four arrival habits below tend to shorten the windows above.
What affects how long recovery takes
The same time difference can take longer for one person and clear faster for another. Four factors mostly explain that spread:
- Direction of travel: eastbound trips (losing hours) tend to take longer than westbound (gaining hours). Recovery speed differs by direction — roughly 1.5 hours per day westbound and about 1 hour per day eastbound (CDC).
- Size of the time difference: the bigger the gap, the more days your body clock needs to catch up. A 4-hour difference clears in a few days, while 9 hours or more often takes over a week.
- Age: older travelers tend to recover more slowly than younger ones.
- Baseline sleep and how often you travel: people who already have sleep problems like insomnia, or who cross time zones in quick succession, tend to feel symptoms more strongly and recover more slowly.
Most of the main symptoms — disrupted sleep and daytime sleepiness — usually ease within one to two weeks, though some, like digestive rhythm, can take a little longer to fully realign. If symptoms last unusually long, or you are considering over-the-counter or prescription sleep aids, talk to a doctor rather than deciding on your own.
What you can do before the trip
Starting a few days before departure, shift your bedtime and wake time gradually toward your destination. A common recommendation is about 15 to 30 minutes per day.
- For eastbound travel (destination time is earlier than home), move bedtime and wake time slightly earlier each day.
- For westbound travel (destination time is later than home), move bedtime and wake time slightly later each day.
- Avoid big swings like pulling an all-nighter the night before; that tends to make the first days worse.
To plan each night's target, the Bedtime Calculator can estimate a bedtime from your goal wake time and the sleep you want to get. It is a useful way to sketch out the first night at your destination. For a fuller walkthrough of the backward-calculation method, see Best Bedtime for Your Wake-Up Time.
How to get over jet lag faster: 4 arrival habits
Once you land, the basics are light, food, and sleep on local time. In practice, these four habits help your body clock align with local time faster (the short naps and careful caffeine are the part that protects nighttime sleep quality).
1. Get morning light outdoors
Morning outdoor light is the strongest cue your body clock uses. A 15 to 30 minute walk outside in the local morning teaches your body that it is daytime here. Even on cloudy days, outdoor light is much brighter than typical indoor lighting, so stepping outside is still worth it.
2. Eat on local time
Shifting breakfast, lunch, and dinner to the local schedule helps anchor your body clock through the digestive system. Even if you are not very hungry, a light breakfast at the local time is often better than skipping it.
3. Keep naps short
If you feel sleepy during the day, a short nap of about 20 to 30 minutes is usually enough to take the edge off. Longer naps can make it harder to fall asleep at night and stretch the recovery out. Try to finish any nap by early afternoon.
4. Use caffeine and alcohol carefully
Caffeine in the morning and early afternoon can help with daytime alertness. Caffeine within roughly six to eight hours of bedtime often interferes with falling asleep, and a stronger dose can extend that window further. For a dose-aware cutoff at the new local time, see When to Stop Caffeine Before Bed. Alcohol can feel like it helps you sleep, but it tends to reduce sleep quality later in the night, so go easy on the first days.
Direction-specific tips
Eastbound (losing hours)
Eastbound trips ask you to fall asleep earlier than your body expects, which is the harder direction for most people. Shifting earlier for a few days before the flight helps. On arrival day, get morning light, and dim bright light (including bright screens) in the evening so your body can wind down on local time. For practical phone-light tactics on the road, see Phone Before Bed: A Practical Guide to Put It Down Without Going Cold Turkey. If you still cannot fall asleep on local time, see When You Cannot Fall Asleep: A Calm Reset for the Night and the Week.
Westbound (gaining hours)
Westbound trips ask you to stay awake longer than usual. On arrival day, try to stay active until the local bedtime. Late-afternoon outdoor light signals to your body that it is still daytime, which makes it easier to hold on until local night. Keep any naps short.
Using melatonin: timing and dose
Melatonin is one of the more studied options for jet lag and may help, particularly for eastbound travel where falling asleep earlier is the harder part.
- Dose: a common range is 0.5 to 5 mg. Starting with a lower dose is generally suggested.
- Timing: typically taken about 30 minutes to a few hours before the local bedtime at your destination.
- Regulation differs by country. In the US it is sold over the counter, while in Japan it is a prescription medicine. Availability and quality of products vary.
- If you take other medications or have an underlying condition, talk to a pharmacist or doctor before using it. Possible interactions include blood thinners, blood pressure medication, antidepressants, immunosuppressants, and contraceptives.
- Pregnant or breastfeeding people, and children, should not use melatonin without medical advice. Safety data in these groups is limited.
- Drowsiness can linger after waking. Avoid driving or operating machinery soon after taking it, and avoid combining it with alcohol or sedative medication unless your doctor has cleared it.
- Use is best kept to a short period rather than ongoing daily intake.
This is general guidance, not a recommendation to use melatonin in any specific case.
On the plane
How you spend the flight has a smaller effect than light and sleep timing on the ground, but a few habits can reduce how rough the first day feels.
- Drink water regularly. Cabin air is dry and mild dehydration can worsen fatigue.
- Go easy on alcohol and caffeine — both can disturb sleep and add to dehydration.
- Try to eat in-flight meals closer to the meal times of your destination, not your home.
- Move a little: ankle circles in your seat and short walks down the aisle when it is safe.
- If you arrive in the local evening, a short rest on the plane can help. If you arrive in the local morning or daytime, try to stay awake so local nighttime sleep can anchor your body clock.
Coming home (the return trip)
The return flight brings jet lag too. The recovery estimates above apply the same way: if your outbound trip was westbound, the trip home is effectively eastbound, so it can feel a bit harder.
Coming home is often easier to manage than fighting jet lag abroad, because you are back to your usual home, meals, and schedule — but expect some lingering effects for a few days. The four arrival habits (morning light, eating on local time, short naps, careful caffeine) work just as well at home. If a back-to-back work trip means you return straight to your normal routine, eating in-flight meals on the meal times of your destination (home) and saving sleepiness for the local night will reduce how rough the first day feels.
For the first few mornings at home, picking a wake time that lands at the end of a sleep cycle can make waking up feel less rough. If you want three wake-time options from a target bedtime, the Sleep Calculator lays out cycle-aligned candidates side by side.
Plan your first bedtime with the Bedtime Calculator
Once you have the four arrival habits and the direction-specific tips in mind, the last decision is what time to actually go to bed on your first local night. Picking a wake time first and working backward keeps the first day from drifting.
The Bedtime Calculator takes your wake time, target sleep duration, and the time you need to fall asleep, and returns three bedtime options (minimum, recommended, and extended). It works for the pre-trip shift as well as the first night at your destination.
For example, if you want a 7:00 local wake time:
- Wake time: 7:00
- Sleep target: 7 hours
- Time to fall asleep: 15 minutes
The calculator returns a recommended bedtime alongside an extended option. On a heavy travel night when sleep onset is uncertain, the extended option gives you a buffer so you still hit your sleep target even if you take longer to drift off.
Once you have the bedtime, start winding down 30 to 60 minutes earlier so sleep comes more easily. If you want a quick shape for those final minutes, the Evening Routine Builder builds a routine that fits the time you actually have, based on whether you want to feel calm, rested, or reset.
FAQ
How long does jet lag usually last?
A common rule of thumb is that your body clock adjusts at roughly one hour per day, so a 5-hour time difference may take 4 to 6 days, and a 9-hour difference can take 1 to 2 weeks. Eastbound travel tends to take longer to recover from than westbound.
How many days does a 6-hour time difference take?
About 4 to 5 days westbound and 6 to 7 days eastbound. Eastbound is usually harder because you have to fall asleep earlier than your body expects. Morning light and meals on local time tend to shorten that window.
How many days does a 9-hour time difference take?
About 7 to 9 days westbound and 9 to 12 days eastbound. Because it often runs past a week, on a short trip you may head home before it fully clears — in that case, easing daytime sleepiness and nighttime insomnia is a more practical goal than a full reset.
How long should a daytime nap be?
About 20 to 30 minutes, finished by early afternoon. Longer naps tend to make it harder to fall asleep at the local night, which stretches the recovery out.
Is the trip home easier?
Often yes, because you are returning to your usual home, meals, and schedule, but expect some lingering effects for a few days. The same four habits (light, food, naps, careful caffeine) still apply.
Related tools
- Bedtime Calculator: For a three-option estimate of your first local bedtime.
- Sleep Calculator: If you want to see when to wake up based on a bedtime you already have in mind.
- Evening Routine Builder: For a calmer wind-down on arrival night to help sleep come more easily.
- A 30-Minute Wind-Down Routine: On heavy travel days, a minimum 30-minute shape can make sleep onset easier on the first local night.
- Evening Routine Guide: The longer 60 and 90-minute templates if your first local evening allows it.
- Best Bedtime for Your Wake-Up Time: A step-by-step guide to picking a bedtime from your wake time, with age-based targets.
- When to Stop Caffeine Before Bed: A dose-aware cutoff for the first local night, when caffeine timing matters most.
- Sleep Cycles Explained: The 4–6 cycles per night and 80–110 minute loop that the calculators are built around.
- Sleep Debt Recovery Plan: If travel left you short on sleep, a 1–2 week plan to catch up gradually.
A note on medical advice
This article is general guidance and is not medical advice. If you have long-lasting insomnia, severe daytime sleepiness, or other symptoms that do not improve, please talk to a qualified healthcare professional.
Sources
- CDC Yellow Book, "Jet Lag Disorder" — https://www.cdc.gov/yellow-book/hcp/travel-air-sea/jet-lag-disorder.html
- Harvard Health Publishing, "Resetting your circadian clock to minimize jet lag" — https://www.health.harvard.edu/blog/resetting-your-circadian-clock-to-minimize-jet-lag-2016090810279
- Sleep Foundation, "How to Get Over Jet Lag" — https://www.sleepfoundation.org/travel-and-sleep/how-to-get-over-jet-lag
- Centers for Disease Control and Prevention (CDC), Travelers' Health — https://wwwnc.cdc.gov/travel/
- Mayo Clinic, "Jet lag disorder" — https://www.mayoclinic.org/diseases-conditions/jet-lag/symptoms-causes/syc-20374027
- Centers for Disease Control and Prevention (CDC), "Jet Lag" — https://wwwnc.cdc.gov/travel/page/jet-lag
- Cleveland Clinic, "Jet Lag" — https://my.clevelandclinic.org/health/diseases/12781-jet-lag