WHAT CAUSES NIGHTMARES?
One important thing to know about nightmares is that they can happen for no reason. Better Health Victoria reveals that "The cause of nightmares isn't known, but it is thought to be the ordinary stresses and strains of growing up. Children who have experienced a traumatic event, for example, tend to have frequent nightmares for the next six months or so."
Professor Harriet Hiscock further explains that "During nightmares...children will usually wake up completely from their bad dream and be scared. They welcome a hug and can remember what happened in the morning."
Children who have an overactive imagination are more prone to nightmares as are children who are sick with a fever. Nightmares can also happen because a child is not getting enough sleep or going to bed too late at night.
AT WHAT AGE DO NIGHTMARES BEGIN?
Your child can start having scary dreams at two years of age. Nightmares will reach a peak between the ages of 3 and 6 years.
Often if a child is under five years, they will not be able to tell the difference between a nightmare and reality. That’s why most of the kids within that range wake up terrified after a nightmare and remain scared for a while before going back to sleep.
NIGHTMARES VS NIGHT TERRORS
Sometimes nightmares get confused with night terrors. Night terrors (also known as sleep terrors) are "dramatic events that present a partial arousal state from deep sleep," and are characterised by, "facial expressions of fear, shouting, screaming, gasps, moans, uncontrollable shouting and agitation." 
After a nightmare, the person wakes up may remember details but a person who has experienced a night terror remains asleep and does not remember anything in the morning, although they may be able to recall aspects of the sleep terror immediately following the episode. Night terrors generally occur in the first third to first half of the night, and rarely during naps. Sleep terrors and sleepwalking are part of a group of parasomnias (undesirable movements and behaviours that occur during sleep) and are linked.
So if your child is experiencing a night terror, they may seem wide awake but they are actually not. Their eyes may be open but they will not realise that you are in the same room. It is best not to try and calm your child if they are experiencing a night terror as you could make the situation worse. Your child will calm down themselves and go back to sleep once the night terror is over.
Though the cause of night terrors is still unknown, it seems to be hereditary. This is because children who experience such sleep-distractions come from families with a history of night terrors, sleep talking, or sleepwalking.
Night terrors affect almost 40 percent of children and a much smaller percentage of adults. However frightening, night terrors aren't usually a cause for concern. Most children outgrow night terrors by their teenage years.
HOW CAN YOU HELP YOUR CHILD DEAL WITH NIGHTMARES?
If your young one tends to experience nightmares more often, there are several things you can do to minimise or brush off the bad dreams. Such things include:
1. Keeping on top of your child’s sleep and ensuring that they get enough sleep in every 24 hour period.
Your child’s sleep needs to be quality sleep –Is their sleep environment encouraging restful sleep? Are they getting enough sleep? Maybe their bedtime needs to be earlier?
2. Establishing a consistent bedtime routine.
Do you have a good bedtime routine that starts two hours before bedtime and lets their brain and body wind down from what went on in the day? Are the books you are reading before bed conducive to restful sleep? i.e. No dragons or monsters or vampires in the stories? TV should be off by 4pm as it is just so stimulating and often as parents we are often not even aware of what our children are watching or what the episodes contain.
3. Discussing the nightmare with your child if there is a reoccurring theme.
If your child is experiencing nightmares with common themes or the same nightmare over and over it would be a good idea to have a chat as it might be something that is in fact bothering your child. Things like starting a new school, the introduction of a younger sibling or even moving house can be enough stress for a young child to start having nightmares. Talk to your child about dreams and explain that everyone has dreams and lots of people have nightmares.
4. Reassuring your child - Don't ignore them!
Give your child a comfort toy so that during the night if they wake up they can give that toy a cuddle and use it as a form of support. Use a night light that is pink, red or yellow as blue or white light actually prohibits the production of melatonin (our sleep hormone). You can also keep their bedroom door open. Get your child to draw our their fears on a piece of paper an hour before bedtime and then put it next to your bed so that you can “keep the fears away” and “keep them safe”. We would never use tactics such as “monster spray” as this showing your child that there is something to be scared of. We want them to know that there is nothing to be afraid of in the first place.
5. Not letting your child sleep with you!
When you're exhausted and at the end of your tether it is really tempting to bring your child into bed with you so you can get some much needed rest. This often backfires with nightmares and it suggests to you child that sleeping in their own bed is causing the nightmare. They may then become scared of sleeping in their own bed and want to sleep with you every night.
 Sleep Terrors in Childhood
Mason, Thornton B.A. et al.
The Journal of Pediatrics, Volume 147, Issue 3, 388 - 392
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Lauryn Stanlake - Infant and Child Sleep Consultant