Imagine the person sleeping next to you suddenly sitting bolt upright and screaming wildly. You try to console them, but they don't respond. Then, after a few minutes, they fall back asleep as if nothing happened. No, they didn't have a nightmare. It's called a night terror. Here's what you need to know about this bizarre and often frightening sleep disorder.
Image: Paranormal Activity
Night terrors are a largely misunderstood and neglected parasomnia, or a category of sleep disorders that involve abnormal physical movements, behaviours, emotions, perceptions, and dreams. Much of this has to do with the fact that it's a very challenging condition to study and that it's often confused with nightmares. But the only similarities between the two is that they happen during sleep. A common problem with assessing or diagnosing night terrors is that most people don't realise what's happening to them.
Table: Carolyn Thiedke, "Sleep Disorders and Sleep Problems in Childhood."
Night terrors go by several names, including sleep terrors, sleep terror disorder, pavor nocturnus, and the formal designation, DSM-IV AXIS I: 307.46 (it's recognised as a psychological disorder by the American Psychiatric Association).
Not Quite Asleep, Not Quite Awake
The key to distinguishing night terrors from nightmares is that the former involves partial waking, while the latter happens during sleep. Indeed, the two occur at vastly different phases of the sleep cycle.
Sleep can be divided into two basic phases, non-rapid eye movement (NREM) and rapid eye movement (REM). The NREM stage, also known as delta sleep and slow wave sleep, can be divided into four sub-stages, each characterised by deeper levels of sleep (e.g. slower breathing, decreased heart rate, etc.). Night terrors tend to happen during the third and fourth stage of NREM -- a stage where dreaming -- and nightmares -- do not occur. They're most common during the first third of the night, often between midnight and 2 AM, but they can also occur during naps. [Related: Why we need to sleep in total darkness]
During a state of partial waking, people are observed to talk or engage in sleepwalking. But during a night terror, individuals exhibit any number of (often) disturbing physical and verbal behaviours.
During a bout of night terror, a person will suddenly bolt upright and scream. They may shout out at a perceived threat, uttering phrases like, "They're going to get me!" Individuals will often thrash around violently and appear to protect themselves from an invisible threat, or worry about some unseen phenomenon (like worms in the bed). Their hearts pound wildly, they break out into a sweat, hyperventilate, and exhibit widened (dilated) pupils. The entire episode can last 10 to 20 minutes, followed by a return to sleep. For chronic sufferers, it can happen as many as three to 16 times per night.
A distinguishing feature of night terrors is that, during the episode, people are utterly inconsolable. A person in such a state cannot be spoken to or comforted. And in fact, it's often dangerous for a spouse or family member to intervene. Most people are unable to explain what happened the next day, and they have often have no memory of the event when they wake up the next morning.
But remarkably, and totally unlike a nightmare, it's very easy for a person to fall back asleep after an episode.
Night terrors are a bit of a mystery to neuroscientists and sleep experts, but there are three associated causes or factors: age, environment, and triggers.
The vast majority of sufferers are boys between the age of five and seven, though it also occurs in girls. Partial awakening, which happens to practically all kids, is developmental for children at this stage in life; up to 17% of preschool-aged children experience disorders of arousal. Typically, sleep terrors decrease in frequency and intensity as children get older. They typically outgrow them by the time they reach school age. The number of episodes usually decreases after age 10.
But after the age of seven, other factors come into play. A slammed door, for example, can trigger an episode in someone prone to the condition. Sleep terrors can also be brought on by emotional tension, stress, fatigue, or conflict, such as a recent divorce or move.
Night terrors may also run in families and have a genetic component. A 2008 study of both identical and fraternal twins showed that the prevalence of sleep terrors was 37% at 18 months and 20% at 30 months. Nearly half of affected children were boys, and 51% were girls. At 18 months, the correlations were significantly stronger for identical twins than fraternal twins.
Night terrors can occur in adults, especially when there is emotional tension or the use of alcohol. But strangely, night terror in adults has been linked to a history of psychopathology and other mental disorders. There may also be links to post-traumatic stress disorder (PTSD) and generalized anxiety disorder. It's also closely related to sleepwalking (a related parasomnia) -- and even frontal lobe epilepsy.
Living With Night Terrors
In most cases, and aside from the night-time inconvenience imposed on parents or spouses, night terrors are not a serious problem. In most cases, it's a condition that mostly goes away.
According to child sleep expert C. Carolyn Thiedke, there's really no good way to treat night terrors aside from reassurance, scheduled awakenings, and diazepam (Valium) in extreme cases (but it should be noted this is rarely done). In the case of scheduled awakenings, it's advised that children be woken-up just prior to the onset of stage three and four NREM (somewhere between the 60 to 90 minute mark into sleep).
Psychologists recommend that the night terror be allowed to run its course and that nearby people not intervene for fear of being injured. It's a good idea to keep a distance, otherwise it can make the situation worse.
In chronic cases, however, psychotherapy and medication can help. Reducing stress or using coping mechanisms may lessen the frequency of night terrors. Talk therapy or counseling can also help in some cases. And in addition to diazepam, it has been shown that l-5-hydroxytryptophan (l-5-HTP) can help children with night terrors.