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 within a few hours of a child falling asleep. The presentation of sleep terrors involves both features of being awake and being asleep.
While sleep terrors are also sometimes referred to as “night terrors”, the former term is more technically correct as “terrors” can occur during any sleep period including naps.
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.
How common are sleep terrors?
Approximately 3% of children experience sleep terrors. While they can begin in infancy, age of onset is usually between 4–12 years of age. Confusional arousals, however, are quite common in infants and toddlers.
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 following puberty most cases naturally resolve.
There are 4 main features that characterize sleep terrors and distinguish them from nightmares:
- TIME OF NIGHT: Sleep terrors, which occur almost exclusively during deep sleep, most commonly occur 1-2 hours after sleep onset (when deep sleep is predominant).
- LEVEL OF RESPONSIVENESS: During a sleep terror, a child will be visibly upset and, while they may have the appearance of being awake (e.g., their eyes may be open), they are actually deeply asleep. 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.
- 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.
- RECOLLECTION: Children have no memory of sleep terrors the next day.
Sleep terrors are very different than nightmares
Nightmares occur during periods of REM (dreaming) sleep, which is for the most part present during the last third of the night. Following a nightmare, a child is usually awake or they can be easily woken. They are responsive to their parents and, most often, comforted by their presence. Following a nightmare there may be a delayed return to sleep as the child is fully awake and may be reluctant to return to sleep due to the bad dream. As children are dreaming during a nightmare and usually awake following it, they may have memory of it the following day.
Sleep terrors versus behavioural night wakings
Sleep terrors also need to be distinguished from “behavioural” night wakings which are common in young children. These wakings are often the result of negative learned sleep associations (also known as “bad habits”). Children who do not have the skill and comfort level of falling asleep independently are usually unable to return to sleep on their own following periods of normal partial arousal that we all have during the night.
In these circumstances, a child may wake up visibly upset at night because she has fallen asleep under one condition (such as while feeding or with a parent in the room) and woken up in a different condition (e.g., alone in a crib or bed). This is akin to us falling asleep in the comfort of our bed and waking up on the couch. We would not be happy!
If poor learned sleep associations are determined to be the cause of your child’s sleep disturbances, sleep training methods that focus on falling asleep independently and appropriate and consistent responding during the night, are often very helpful.
For information on risk factors and management strategies for sleep terrors stay tuned for our follow up article on it!
The information provided by Dr. Cohen is not intended to be a substitute for professional advice. Individuals are encouraged to speak with a physician or other health care provider if they have concerns regarding their child’s sleep and before starting any treatment plan. The information provided by Dr. Cohen is provided with the understanding that Dr. Cohen is not rendering clinical, counselling, or other professional services or advice. Such information is intended solely as a general educational aid and not for any individual problem. It is also not intended as a substitute for professional advice and services from a qualified healthcare provider familiar with your unique facts.