Sleep Terrors or Nightmares: How Can You Tell? |
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First it may be helpful to rule-out night wakings that are due to behavioural factors such as poor learned sleep associations (otherwise known as ‘bad habits’). For more information on these types of wakings, see: Behavioural Night Wakings in Young Children.
This article will focus on describing sleep terrors and nightmares and outlining the main distinguishing features of each.
Sleep Terrors:
Sleep terrors are the same class of behaviours as sleeptalking, sleepwalking, and confusional arousals (a milder version of sleep terrors). These behaviours are classified as partial arousal parasomnias which are sudden arousals during deep sleep. As deep sleep is predominant in the first-third of the night, sleep terrors usually occur during the first part of the night. The presentation of sleep terrors involves both features of being awake and being asleep.
Children who have sleep terrors appear to be frightened, confused, and agitated. Screaming, crying, and ‘thrashing’ around are often involved. However sleep terrors do not involve dreaming as they do not occur during periods of dreaming sleep known as rapid eye movement (REM) sleep. Parents often find comfort in learning that sleep terrors are not indicative of an underlying psychological problem and do not result in psychological harm. During these episodes, children are unaware of their own behaviour. Thus they are much worse to watch than to experience.
Approximately 3% of children experience sleep terrors. While they can begin in infancy, the average age of onset is between 4 – 12 years of age. Confusional arousals, however, are quite common in infants and toddlers. The good news is that the prevalence of sleep terrors decreases markedly with age. This is because there is a rapid decline in the amount of deep sleep in young childhood through adolescence. By age 8, 50% of children with sleep terrors no longer experience them, and by puberty most cases naturally resolve.
Nightmares:
Nightmares occur almost exclusively during REM (dreaming) sleep. While dreams can also occur during non-REM sleep, those that occur during REM sleep are more vivid and likely to be remembered. Nightmares are far more common than sleep terrors, with 75% of children having at least one nightmare. Research has shown that chronic nightmares (defined as the occurrence of nightmares for more than 3 months) occurs in almost 25% of children ages 2-5 years of age. Periods of REM sleep get progressively longer as the night progresses, with most REM sleep occurring during the last third of the night.
There are 4 main features that distinguish sleep terrors from nightmares.
1. TIME OF NIGHT: The times in which these behaviours occur are particularly helpful in determining whether a child is having a sleep terror or nightmare. Sleep terrors, which occur almost exclusively during deep sleep, most commonly occur 1-3 hours after sleep onset (when deep sleep is predominant). Nightmares on the other hand, occur exclusively during periods of REM sleep, which is for the most part present during the last third of the night.
2. LEVEL OF RESPONSIVENESS: During a sleep terror a child will be visibly upset and while they are asleep they may have the appearance of being awake (e.g., their eyes may be open). Because they are sleeping, they are not aware of or comforted by their parents’ presence or intervention. When a child is having a sleep terror she is also difficult to wake. Some children may briefly wake following a sleep terror, only to quickly return to sleep. On the other hand, following a nightmare, a child is usually awake or they can be easily woken. Following a nightmare, children are responsive to their parents and, most often, comforted by their presence.
3. READINESS TO RETURN TO SLEEP: Once a sleep terror has run its course (they can last anywhere from minutes to an hour), there is a rapid return to a deeper, calmer sleep. This is because the child was never truly awake. In contrast, following a nightmare there is often a delayed return to sleep as the child is fully awake and may be reluctant to return to sleep due to the bad dream.
4. RECOLLECTION: Children have no memory of sleep terrors the next day (unless they were woken). As children are dreaming during a nightmare and usually awake following it, they may have memory of it the following day.
For more information on risk factors and management strategies for sleep terrors and nightmares see Sleep Terrors and Nightmares: What Parents Can Do.
About the Author
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Dr. Nicky Cohen
Dr. Nicky Cohen, a Clinical Psychologist, welcomes questions on parenting your infant, toddler and preschooler to sleep. Learn more about Dr. Nicky Cohen
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Ronalda Gallant | March 4, 2009 at 5:45 pm - §
i live below a family of young children. Sometimes I don't know what kind of crying I'm hearing. Today was awful as I heard gutteral sonding crying upstairs. I called the super. He told me that the child has day terrors which can last for hours.She is "awake" seemingly but her eyes are not focussed. The crying/screaming is terrible to hear. Do you have any facts or helpful ideas about this?It's only in the daytime when this occurs. Thank you.
eric blades | May 8, 2009 at 1:50 pm - §
I have a 2 year old that has been a bloody screamer from day one. She has always been a high needs baby and cried for hours if you didnt hold her or give her what she wants. She's a lot better at 2. But she still wakes up from a nap or sleep going from absolutely quiet to full out screaming and crying. The weird thing is that she is actually awake. She is fully aware of her surroundings. She will stand there throwing her hands and rubbing her face. If any of us even blink the wrong way she will intensify. She gradually steps toward me a couple of feet every 5 minutes while screaming. She gets worse if I talk to her and even worse if I don't. When she finally reaches me, she will try to fight if I go to pick her up. But once I actually do, she lays on my chest and starts to calm. 15 minutes later she smiles and acts as if nothing happened. Its weird. It reminds me of night terrors except with full awareness and interaction. Am i dealing with something new?