I talk a lot about melatonin in various articles on this website and this is because of the importance it has in getting a good night’s sleep. 
Melatonin is a natural hormone produced in the blood. It is at its lowest levels during the day and its highest levels at night.
Therefore, when your melatonin levels are at their highest, your body is ready for sleep.
The use of melatonin supplements to boost or aid sleep is becoming more prevalent and therefore I thought it was important to discuss the side effects of melatonin supplements.
Why Do People Take Melatonin Supplements?
Melatonin supplements are most often used to treat sleep disorders that are related to circadian rhythm. 
Just in case you weren’t aware, circadian rhythm is your sleep/wake cycle – a 24-hour internal clock that runs in the back of your brain and tells you when you should be awake and when you should be asleep.
This explains why you feel alert and energized or sleepy and drowsy around the same time each day.
The supplements are most commonly used by people who suffer with insomnia and night-shift workers.
In the case of night-shift workers, they obviously work at night (when melatonin levels are high) and sleep during the day (when melatonin levels are low). This can cause havoc with the sleep/wake cycle, but night-shift workers may find that the quality and duration of their sleep (during the day) is a lot better with the introduction of melatonin supplements.
As a night-shift worker, the supplements should be taken before you sleep, but not before you have driven home.
Melatonin is often used to treat jet lag, yet another time when your circadian rhythms may be totally out of sync.
Physicians recommend it should be taken a few hours before your intended bedtime and then continue taking it for a few days after you’ve arrived at your destination.
What Else Do You Need to Know?
Melatonin supplements are freely available over the counter in the United States.
However, in Australia and most European countries these supplements are only available by prescription, and are strictly for adult use only.
There have been various studies in to the effects of melatonin supplements and it is widely agreed that they are fine for short-term use.
Unlike other sleep-inducing drugs, you are highly unlikely to become dependent on melatonin. You won’t experience the “hangover effect” or a diminished response, which can be quite common with other sleep medications.
It is suggested that melatonin is taken in doses of 0.3mg-10mg, although a formal dose has never been established.
You should also be aware that 0.3mg closely resembles the natural levels of melatonin production in the body, whereas larger doses can cause melatonin to peak at much higher levels in the blood.
What Are The Side Effects of Melatonin Supplements?
There are no actual studies into the longer term effects of melatonin supplements. The fact that these supplements are being used more widely than ever before is a cause for concern about the potential side effects.
There are some medical practitioners who are extremely apprehensive about recommending these supplements because it is believed that they may decrease the natural production of melatonin in the body.
According to studies on the short to medium-term use of melatonin supplements the most common side effects are:
- Headaches
- Dizziness
- Nausea
- Drowsiness
- Agitation
The are also a few less common side effects you should be aware of:
- Mild feelings of anxiety or depression.
- Abnormally low blood pressure.
- Mild tremors.
- Confusion or disorientation.
- Stomach cramps.
Melatonin Supplements for Children
Getting your children to sleep is a whole new subject (and one I will discuss in detail in future articles), but many parents give their children melatonin supplements if they are having trouble sleeping. 
I mentioned earlier that most European countries will only issue melatonin supplements to adults and by prescription. However, it is very different in the United States.
Most health food stores and online sellers offer melatonin supplements specifically aimed at children, e.g. a popular type of supplement is the “gummy”, which is reminiscent of a chewable sweet.
Nevertheless, I think it’s important to note that the Food and Drug Administration (FDA) has never approved nor evaluated the use of melatonin supplements for children.
There has never been a specific cause for concern in giving children these supplements, but most experts and healthcare professionals are reluctant to recommend their use. Children are part of a sensitive group, due to the fact they are young, still growing and still developing.
It should also be noted that melatonin is transferred to breast milk, so breastfeeding mothers should be aware that it can cause extreme sleepiness in nursing infants.
Other Potential Side Effects of Melatonin Supplements
Melatonin supplements may interact with various medications, including:
- Contraceptive drugs.
- Diabetes medication.
- Immunosuppressants (medications that suppress the immune system).
- Anticonvulsants.
- Blood-related medications, such as anticoagulants and anti-platelet drugs.
Melatonin causes a slight drop in body temperature. This isn’t a particularly big deal, but may be of concern to those of you who have difficulty in keeping warm.
A study also found that melatonin when mixed with the sleep drug zolpidem could aggravate the already known adverse effects that zolpidem has on muscle performance and memory.
So, Are Melatonin Supplements Safe to Take?
Melatonin supplements have never been linked to any serious side effects, irrespective of the dosage.
However, I reiterate that there are no studies into the long-term effects of taking the supplement, but melatonin is perfectly safe for short-term use.
You can increase melatonin levels naturally as well.
One way is to reduce the amount of artificial light you are exposed to before bedtime. You can dim the lights in your home a couple of hours before you hit the sack.
This is typically why you are told to turn off the TV and avoid your smartphone, laptop and tablet in the hours leading up to sleep.
The artificial light can start to play tricks on the brain, making the body think it’s daytime, thus decreasing the production of melatonin.
On the contrary, this is why it’s important to get lots of natural light during the day. You are signaling to the brain and body that it is time to be alert and awake, so melatonin levels will naturally reduce at this time.
All-in-all, I would say that it does appear that these supplements are an effective aid for sleep, but keep in mind the lack of research into its long-term use.
I would further suggest that use by sensitive groups, such as infants and children, and expectant or breastfeeding mothers, should involve first consulting with a medical professional.