Circadian rhythm disorders
Jet Lag
Temporary sleep and daytime problems after flying across time zones, while your body clock catches up with local time.
Overview
Jet lag occurs when you travel quickly across two or more time zones and your body clock is still set to your home time. You may feel sleepy at the wrong times, wake during the night and feel foggy, irritable or unwell.
Travelling east is usually harder than travelling west, because it requires your body clock to move earlier, which it does less easily. Symptoms generally improve as your clock adjusts, which often takes about a day for each time zone crossed.
Timing light exposure, adjusting your sleep schedule before travelling and, for some people, using melatonin can speed adjustment.
Common symptoms
- Difficulty falling asleep or waking too early at the destination
- Daytime sleepiness and fatigue
- Poor concentration
- Irritability
- Stomach upset, constipation or changes in appetite
- General feeling of being unwell
Causes and risk factors
- Crossing multiple time zones quickly
- Travelling east
- Sleep loss during travel
- Older age
- Alcohol and caffeine during travel
How it is diagnosed
Jet lag is diagnosed from your symptoms and recent travel: insomnia or sleepiness, with reduced daytime function, starting within a day or two of travel across at least two time zones. Testing is not needed.
Treatment options
Timed light exposure
Seeking or avoiding light at specific times helps shift the body clock towards local time.
Pre-travel schedule shift
Moving bed and wake times an hour a day toward the destination time zone before departure.
Melatonin
Taken at local bedtime after arrival, it can reduce jet lag symptoms for many travellers, particularly when flying east.
Short-acting sleep aids
A clinician may occasionally suggest one for short-term use.
What you can do yourself
- Adopt the destination schedule as soon as you board
- Get daylight at the right time for your direction of travel
- Stay hydrated and limit alcohol on the flight
- Keep naps short, under 30 minutes
- Use caffeine carefully to stay alert during the day, not in the evening
When to see a doctor
- You travel often and jet lag affects your work or health
- Sleep problems continue long after returning home
- You want advice on melatonin or sleep aids with other medicines
Frequently asked questions
Why is flying east worse?
Flying east requires your clock to shift earlier, which is harder for most people than shifting later. Westward travel aligns better with the body clock's natural tendency to run slightly longer than 24 hours.
How long does jet lag last?
A common rule of thumb is about a day of adjustment per time zone crossed, but it varies with direction, age and how well you manage light and sleep.
Does melatonin help jet lag?
Research reviews suggest melatonin taken close to local bedtime at the destination can reduce jet lag symptoms for many travellers. Check with a clinician if you take other medicines.
Should I nap after landing?
A short nap of 20 to 30 minutes can help, but long naps make it harder to sleep at local bedtime. Try to stay awake until a reasonable local bedtime.
Sources
This page is general information, not a diagnosis or medical advice. Read our medical disclaimer.