How it works
What does melatonin do?
Melatonin is a hormone that occurs naturally in the body. It helps regulate your body clock so you can sleep better.
Melatonin will usually be given to you by a specialist at a hospital at first.
Melatonin should be used alongside good “sleep hygiene” techniques. These include:
- making sure that your room is dark and the right temperature
- avoiding looking at backlit screens around bedtime
- doing exercise during the day (but not the last couple of hours before bed)
- avoiding taking naps during the day
The aim of using melatonin is to establish a good sleeping pattern with the lowest effective dose.
How long does melatonin take to start working?
Melatonin starts to work about an hour after you take the dose. However, it can take a few days of taking melatonin for its full effect to develop.
Melatonin will start helping your body to re-establish a normal sleep pattern after you have taken it for a week or so.
The effects of a dose of melatonin can last for around four to eight hours after taking it.
How long will I need to take melatonin?
You and your doctor should talk about how long you need to take melatonin before you begin treatment.
Some people taking melatonin to help with sleep may take it for up to 13 weeks (three months) to make sure a normal sleep pattern is established.
Some people may need to take melatonin for longer (on the advice of their doctor).
People with attention deficit hyperactivity disorder (ADHD) usually only need to take melatonin for three to four weeks to get a normal sleep pattern again.
To get the best effect from melatonin, it is best not to miss any doses.
Keep taking the melatonin until you and your doctor agree that it is no longer needed.
Your doctor needs to know if...
You need to talk to your doctor or pharmacist before starting treatment with melatonin if any of the following apply to you:
- you have an autoimmune disease like juvenile arthritis, multiple sclerosis, lupus or type 1 diabetes
- you have liver or kidney disease
- you have allergies to melatonin or lactose
You should only take melatonin as agreed with your doctor
Make sure that you know your dose. If it is not written on the label, check with your pharmacist or doctor.
Take your melatonin one to two hours before you go to bed, and after some food. This can be a small snack before bedtime, like a biscuit or two, if you have your evening meal more than two hours before you go to bed.
Do not break or chew the modified-release tablets. This is because they have a special system in them to deliver the medicine into your body slowly, over a few hours. Swallow the tablet whole with at least half a glass of water while sitting or standing.
You should make sure that you do not watch TV or use a computer or mobile phone at least an hour before going to bed, as light from these can stop your body from making its own melatonin.
What if I miss a dose?
If you remember later during the evening, before you go to bed, take it as soon as possible.
If you forget to take it by bedtime, just start again the next evening.
Do not take a double dose.
What will happen if I forget to take my melatonin?
If you forget to take your tablets for a few days, you may get your old symptoms back. This means that you should talk to your doctor about it.
You do not get discontinuation or withdrawal symptoms if you forget to take melatonin.
Stopping the use of melatonin
You should not get any harmful discontinuation or withdrawal effects if you stop taking melatonin.
However, you may get your old symptoms back.
If you are on a high dose, then the doctor may wish to reduce the dose slowly before stopping it completely.
The information on this page was reviewed by the College of Mental Health Pharmacy in March 2020.