What is melatonin?

Melatonin is a hormone that is produced by the pineal gland in the brain. Melatonin levels vary in twenty-four hour cycles and are controlled by our body clock. Normally its production is reduced by being in bright light. Levels increase at night. This is why it is often called ‘the hormone of darkness’. But in fact the word melatonin itself means ‘skin whitening’. This is due to how it affects skin in some animals. But it does not change the skin colour of humans. Some plants have small amounts of melatonin as well. These include plants we use as food.

Where is it found?

Once it gets into the blood melatonin goes to all parts of the body.

What does it do?

Melatonin appears to be important in helping regulate the internal body clock’s cycle of sleep and wakefulness. Other claims are made for it: it has anti-oxidant and free radical scavenging properties and some say it has anti-cancer and anti-ageing effects, but there is no proof for this in humans.

In regards to sleep, your blood melatonin level starts to go up about two hours before you go to sleep. It helps establish the conditions for sleep and your core body temperature to go down slightly at this time.

What can you use it for?

Melatonin is used to treat insomnia. There are two ways that you can use it. The first is as a sedative, to make you feel sleepy. This is the most common use. The second is to help reset your internal body clock to a different time in conditions where it is out of synchrony with time of day, such as with jet lag or advanced or delayed sleep phase syndrome. In these cases melatonin therapy at night is often combined with Bright Light Therapy. Light is applied in the morning (usually using outdoor light) in the case of jet lag or delayed sleep phase syndrome or in the evening (using special lights) in the case of advanced sleep phase syndrome (see also Delayed Sleep Phase Syndrome). Recently a synthetic form of melatonin has also been developed to treat depression.

How much should you take?

Daily doses of 0.5mg to 5mg appear similarly effective, although sleep onset may be quicker at the higher dose. There does not appear to be any advantage in taking more than this. The most commonly available preparation in Australia contains 2mg. It is in a slow release form to last throughout the night, much like the naturally-occurring melatonin. However the slow release formulation does not allow a short high peak level which some argue helps with sleep onset. All melatonin tablets need a doctor’s prescription in Australia (but not in North America).

When should you take it?

If you take melatonin to go to sleep, the best time (for the slow release type particularly) is about an hour before you go to bed. However, some people feel a “wave” of sleepiness some twenty minutes after taking it and make the most of this by being in bed ready to sleep at this time. You may have to experiment a bit with when you take it. Discuss this with your prescribing doctor.

You can also take it to adjust the body clock, for example when you are crossing time zones to minimise jet lag. You should take it close to target bedtime at your destination. The benefits are greater where more time zones are crossed and for eastward flights more than westward flights.

Can it cause problems?

Melatonin can cause sleepiness and so should not be taken before driving or operating machinery.
Melatonin’s main benefit is in reinforcing external cues for sleep or as a tool to help shift sleep-wake rhythms. Long term use of melatonin is only appropriate if prescribed because of a significant, underlying sleep disorder.
Side effects are uncommon. These and its compatibility with your other medicines should be discussed with your prescribing doctor.

What can children use melatonin for?

In children, melatonin is typically used to treat difficulties with going to sleep or staying asleep. It may benefit children who are developing normally as well as children with Attention Deficit Hyperactivity Disorder, autism, other developmental disabilities or visual impairment.

For most children with sleep problems, there is a specific cause which should be identified and treated before melatonin is considered as an option. For example a child might not be able to get to sleep due to their anxiety. If the child is anxious, there are things to try first such as relaxation techniques and visual imagery. In some cases, the sleep problem may be related to the child’s behaviour. If this is the case the parents should try to change the child’s behaviour at bedtime.

How much melatonin should my child take?

If your child’s paediatrician or sleep specialist has prescribed melatonin, the dose will depend on your child’s age. A young child needs less than an older child.

Amounts may vary from 0.5mg to 6mg. There does not seem to be any reason to take more than this. All forms of melatonin need a doctor’s prescription in Australia. The most common preparation in Australia is 2mg in a tablet form and this is available from chemists with a prescription. It is a slow release form to last all through the night. This is much like the melatonin that occurs naturally. Melatonin is also available in liquid form or in immediate release tablet form from compounding pharmacies.

When should my child take it?

To help your child go to sleep, the best time to take the melatonin is around thirty to sixty minutes before you want them to go to bed. You may need to try giving it at different times to work out when is best for them. Discuss this with your child’s doctor. Be sure to use it along with a good pre-bed routine. The bedroom should be dark and comfortable. It is important that it is free from electronic media (such as televisions, electronic games, and phones) which may distract the child and make it difficult to sleep. Children should not use computers for at least an hour before going to bed. A light snack before bed is okay, but drinking and eating should be avoided if possible for at least two hours before bed.

Can melatonin cause problems for children?

In the short term, melatonin seems to work well and be safe. Only a few studies have looked at its long term use in children. But those that have, suggest that it is safe. Long term use is only appropriate if it is because of an specific sleep issue, such as may be seen in children with developmental problems or visual impairment. Side effects in children are very rare. When people report them, it is not yet certain if they are caused by melatonin or by something else. You should talk about this with your doctor.