How long does jet lag last?

Roughly one day of adjustment per time zone crossed, and eastward travel is slower than westward because your body clock naturally runs a little longer than 24 hours. Shifting an hour a day before you fly can cut the post-arrival slump in half.

Is it easier to fly east or west?

West. Delaying bedtime is easier than advancing it, so a west-bound trip typically settles in two-thirds the time of the same distance east-bound.

When should I get light — and when should I avoid it?

Flying east, seek bright morning light at your destination and avoid it in the evening. Flying west, do the opposite: get evening light and avoid bright morning light for the first couple of days. Light is the strongest signal your body clock has.

Does melatonin help with jet lag?

The evidence is best for eastward travel using a small dose in the destination's early evening. It is a timing signal, not a sedative, so dose and timing matter more than strength. Check with a clinician if you take other medication.

Jet Lag Calculator

Shift your body clock before you fly instead of after you land. Enter your trip and get a night-by-night plan for the days leading up to departure.

Time zones crossed

Direction

Usual bedtime

Pre-flight shift plan

Nights before departure	Bedtime	Wake time
5	10:00 PM	6:00 AM
4	9:00 PM	5:00 AM
3	8:00 PM	4:00 AM
2	7:00 PM	3:00 AM
1	6:00 PM	2:00 AM

Without preparation, expect roughly 6 days to feel normal after landing. Following the plan above typically halves that.

Light

Get bright light early in the morning at your destination and dim the evening. Morning light pulls your clock earlier.

Caffeine

Use it in the destination morning only, and stop at least 8 hours before your new bedtime. Caffeine that late keeps you locked to the old time zone.

Home again and still sleeping badly after a week? Travel may not be the only factor. Re-check your schedule, light exposure, room environment, and accumulated sleep loss with the sleep debt calculator. Persistent insomnia or severe daytime sleepiness is worth discussing with a clinician.

FAQs

How to use a jet lag plan

Direction matters

Flying east usually feels harder than flying west because it asks your body clock to move earlier. The plan shifts sleep and wake times in small steps before you leave so the adjustment on arrival is smaller.

The levers you control

Light: bright daylight at the right time of day is the strongest signal to your body clock; avoiding bright light at the wrong time matters too.
Sleep timing: shift bedtime gradually in the days before departure if your schedule allows.
Meals and caffeine: eat on destination time once you land and keep caffeine to the morning.
Short trips: for one or two nights away, it can be easier to stay on home time.

Comfort on the way

A travel pillow, eye mask and earplugs make it easier to sleep on the plane when the plan says to. Melatonin and other sleep aids are a medical decision — ask a doctor or pharmacist before using them. Calculators give general estimates from the numbers you enter. They are planning aids, not medical advice, and they cannot account for health conditions, medications or individual differences.

What the calculator cannot know

A time-zone plan can organize sleep and light timing, but it cannot predict exactly how fast your body clock will shift. Work schedules, sleep loss before the trip, overnight flights, age, chronotype, and daylight exposure all change the experience. Treat the schedule as a starting plan and adjust it if you are dangerously sleepy or unable to function normally.

Common questions

How many days does it take to adjust?

A common rule of thumb is about one day per time zone crossed, often a little faster flying west. Shifting your schedule before departure and timing light exposure well can shorten that.

Should I nap when I arrive?

A short nap of 20–30 minutes early in the afternoon can take the edge off without ruining your first night. Long naps late in the day tend to delay adjustment.