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The Night is Dark…


6-year-old Jon is brought into the emergency hours by his parents at 10 pm. They went into his room to take him to the toilet as usual and he started screaming at them. He was sweaty and in a state of panic. It took half an hour or so to calm him down and is unable to tell them what has upset him.

Bottom line

Parasomnias are physical disturbances that occur during sleep

Night terrors occur during the first part of the night and classically present with a blood-curdling scream, extreme distress, and autonomic arousal coupled with amnesia for the event (unlike nightmares)

Sleepwalking and night terrors are not dangerous in themselves but, if recurrent, may reflect underlying psychosocial distress or medical pathology.

What are parasomnias?

Parasomnias are physical phenomena occurring in sleep. They can be classified as arousal parasomnias (such as night terrors and somnambulism), sleep-wake transition issues (hypnogogic and hypnopompic jerks), and rapid eye movement (REM)  sleep disorders (including nightmares).  For a terrific review of the parasomnias read this great summary from Mason and Pack in the aptly named, Sleep.

What are night terrors?

They are sudden episodes of apparent terror that often begin with an earsplitting scream, followed by partial amnesia of the episode. They may be accompanied by a state of extreme autonomic arousal and emotional distress. Night terrors take place in the first couple of hours of the night’s sleep when the child is transitioning from slow-wave sleep to a lighter non-REM sleep state. They occur in 1-6.5% of children.

What are the stages of normal sleep?

Sleep should occur in cycles of non-REM sleep followed by shorter periods of rapid eye movement sleep. In stage 1 of non-REM sleep your eyes are closed but you can be woken very easily. By stage 2 your heart rate begins to slow and you’re temperature drops as your body prepares for deep stage 3 and 4 sleep. The duration of each stage of sleep is highly variable but the first episode of REM sleep typically occurs around 90 minutes after falling asleep. It’s at this time when night terrors are most common.
The normal hypnogram

What about somnambulism?

It’s just a fancy way of saying sleepwalking.  Sleepwalking is incredibly common and has a lifetime prevalence of up to 40% though regular episodes only occur in 2 to 3% of children, usually between the ages of 4 and 8 years. About 5% of the adult general population continues to walk in their sleep.

There is no difference in incidence between boys and girls though it is 10 times more common in first-degree relatives.

Are some children more prone to parasomnias than others?

Other than the genetic predisposition described a number of cofactors have been linked to parasomnias including:

  • sleep deprivation
  • medications including neuroleptics, antihistamines and sedatives as well as stimulants
  • a poor sleep environment (too noisy or too hot)

Medical conditions such as sleep-disordered breathing and restless leg syndrome have also been linked with an increased incidence of night terrors and sleepwalking.

What are the long-term consequences of disordered sleep?

It has been suggested that disordered sleep may lead to increased psychological problems in school-aged children. Children who do not sleep well may be more withdrawn, display signs of anxiety or depression or may have problems with attention.  However correlation does not indicate causation. It is just as likely that children suffering from depression, anxiety or social stress sleep poorly.

So just how long should children sleep for?

The consensus opinion of the National Sleep Foundation is summarised below:

AgeRecommended hrsMay be appropriate hrsNot recommended hrs
11More than 11
Young adults (18-25 yrs)7 to 96Less than 6
11More than 11
Teenagers (14-17 years)8 to 107Less than 7
12More than 12
School-aged (6-13 years)9 to 117 to 8Less than 7
14More than 14
Preschoolers (3-5 yrs)10 to 138 to 9Less than 8
15 to 16More than 16
Toddlers (1-2 yrs)11 to 149 to 10Less than 9
16 to 18More than 18
Infants (4-11 months)12 to 1510 to 11Less than 10
18 to 19More than 19
Newborns (0-3 months)14 to 1711 to 13nLess than 11

Can waking a sleepwalker kill them?


Can you prevent night terrors or sleepwalking?

A number of pharmacological and non-pharmacological methods have been tried out. Given the potential downside and lack of evidence of efficacy of benzodiazepines and tricyclics, behavioural interventions are safer. Some children are unfortunate enough to suffer from regular episodes of disturbed sleep. Behavioural modification of the sleep cycle has been shown to be effective worked in a small case series.

Parents note what time of night time of night their children are affected and look out for signs of autonomic arousal such as sweating or increased movements. If they are able to anticipate an attack then they can fully wake the child for five minutes or so before letting them go back to sleep. By manipulating the sleep-wake cycle in this way future attacks can be aborted.

You discuss potential contributing factors for Jon’s night terrors, including his cold bedroom, the freezing winter wind whistling outside, and recent use of anti-histamines to treat his runny nose. You suggest a watchful waiting approach and counsel his parents on good sleep hygiene. You also advise them of how best to treat him should the problem recur.


Mason, T. B. A., and Allan I. Pack. “Pediatric parasomnias.” SLEEP-NEW YORK THEN WESTCHESTER- 30.2 (2007): 141.

Kales, Anthony, et al. “Hereditary factors in sleepwalking and night terrors.” The British Journal of Psychiatry 137.2 (1980): 111-118.

Ohayon, Maurice M., Christian Guilleminault, and Robert G. Priest. “Night terrors, sleepwalking, and confusional arousals in the general population: their frequency and relationship to other sleep and mental disorders.” Journal of Clinical Psychiatry 60.4 (1999): 268.

Lask, Bryan. “Novel and non-toxic treatment for night terrors.” BMJ: British Medical Journal 297.6648 (1988): 592.

Guilleminault, Christian, et al. “Sleepwalking and sleep terrors in prepubertal children: what triggers them?.” Pediatrics 111.1 (2003): e17-e25.

Frank, Natalie C., et al. “The use of scheduled awakenings to eliminate childhood sleepwalking.” Journal of Pediatric Psychology 22.3 (1997): 345-353.

Stein, Mark A., et al. “Sleep and behavior problems in school-aged children.”Pediatrics 107.4 (2001): e60-e60.

Hirshkowitz, Max, et al. “National Sleep Foundation’s sleep time duration recommendations: methodology and results summary.” Sleep Health 1.1 (2015): 40-43.

Carskadon, Mary A., and William C. Dement. “Normal human sleep: an overview.” Principles and practice of sleep medicine 2 (2000): 16-25.



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