• Jet lag is a temporary mismatch between your body’s natural sleep-wake cycle and a new time zone. This can cause sleep problems, daytime tiredness, irritability, trouble thinking clearly, and digestive discomfort.
• 
  Jet lag is usually worse the more time zones you cross. Travelling east tends to cause more symptoms than travelling west because it’s harder for the body to adjust to an earlier bedtime.

Melatonin is a natural hormone released when it gets dark. It signals to your body that it’s time to sleep and helps regulate your internal body clock.

Taking melatonin for a short period can help your body adjust to a new time zone and ease symptoms of jet lag by promoting sleepiness at the right time.

Melatonin can be prescribed for adults aged 18 and over to reduce symptoms of jet lag. You’ll be asked to complete an online consultation. A prescriber will review your answers to check whether melatonin is safe and suitable for you.

The usual dose is 3 mg (one tablet) once daily for up to 5 days.
If 3 mg doesn’t help, your prescriber may recommend increasing to 6 mg (two tablets taken together).
Melatonin should not be taken for more than 5 consecutive days. Always follow the instructions on your medicine label and do not exceed the recommended
dose.

• Take your first dose on arrival at your destination at your usual bedtime.
• Take it between 20:00 and 04:00 at your destination. Taking it outside this window may reduce its effectiveness or worsen jet lag.
• Take melatonin at least 2 hours before or after a meal (or 3 hours after a meal if you have diabetes or impaired glucose tolerance).
• Avoid alcohol and caffeine before bedtime.
• Keep a good sleep routine and sleep in a dark, calm environment.

No. Alcohol can worsen jet lag symptoms and interfere with sleep, so you should avoid drinking alcohol while taking melatonin.

Melatonin can cause drowsiness and reduced alertness. Do not drive or operate machinery within 8 hours of taking melatonin.

Common side effects include:

• Drowsiness
• Headache
• Dizziness or feeling disoriented

Other possible risks include increased chance of falls, accidents, memory problems, dependence or withdrawal symptoms, and potentially an increased risk of dementia (mainly with long-term use).

Yes. Your prescriber will check for interactions during your consultation.
Melatonin can interact with medicines such as fluvoxamine, quinolones, carbamazepine, and rifampicin, and may increase drowsiness or lower blood pressure when combined with many other medicines.

If you take medications such as antidepressants, antihistamines, antipsychotics, opioids,
blood pressure medicines, or drink alcohol, and experience dizziness or excessive sleepiness, stop melatonin and seek medical advice.

Melatonin does not stop contraception or HRT from working.
However, melatonin levels in the body may increase when taking the combined pill or HRT.

You should not take melatonin if you are allergic to melatonin, or any tablet ingredients or

• Have liver or kidney problems
• Have epilepsy or a history of seizures
• Have neurological conditions or autoimmune disease
• Have diabetes
• Have alcohol dependency or acute alcohol intake
• Have sleep apnoea or other sleep disorders

You can support better sleep by:

• Relaxing before bed (warm bath, calm music)
• Avoiding caffeine close to bedtime
• Avoiding heavy meals and alcohol before sleep
• Drinking plenty of water
• Limiting screen time before bed
• Using blackout curtains, eye masks, or earplugs
• Taking short daytime naps (no more than 15–20 minutes) if needed