Once prescribed only for certain sleep disorders, melatonin has become a quick fix for anyone struggling to sleep. But as its use grows, so does concern around how and when it's used – and for how long.

What it is
Melatonin is a hormone produced by the pineal gland in response to darkness. It signals to your body that it’s time to sleep, helping regulate your circadian rhythm. Synthetic melatonin mimics this effect, but how you use it is crucial.

How it works
Taken 30 to 60 minutes before bed, melatonin can help you fall asleep — useful for jet lag or delayed sleep-phase disorders. But taken too early, too late, or at the wrong dose, it can confuse instead of help your rhythm.

When it helps
— Jet lag and time-zone shifts: supports circadian adjustment when used briefly.
— Specific sleep-phase disorders: may advance or delay sleep onset under supervision.
— General insomnia: evidence shows only mild improvement, often short-term.

Regulation matters
In the UK, melatonin is prescription-only — intended for defined conditions and limited use (typically ≤ 13 weeks). In the US, it’s sold as a supplement, where testing and dosage accuracy vary widely.

What research shows
Short-term side effects include:
— Drowsiness
— Headaches
— Dizziness
— Irritability

Long-term side effects include:
— Increased risk of obesity and type 2 diabetes mellitus due to disturbed sugar metabolism
— Interference with individual hormonal balance including steroid, thyroid hormones and insulin
— Disturbed menstrual cycles or fertility due to interaction with the endocrine system
— Decreased semen quality

Better rest, naturally
Before reaching for melatonin, support your body’s rhythm:
— Morning light exposure
— No screens 1 hour before bed
— Consistent routine
— Light evening meals, no late caffeine
— Calm wind-down time

If sleep issues persist, seek medical guidance.