Sleep Terrors

It occurs mainly during the first third of the night (2 to 3 hours after falling asleep) and lasts 1 to 10 minutes.

During an episode, the individual manifests an intense fear (for example, rapid breathing, sweating, dilatation of the pupils) and he or she is usually unresponsive to the efforts of others to awaken or comfort him or her.

Upon awakening, the individual usually keeps no memory of the episode. Like sleepwalking, sleep terrors occur primarily in childhood and normally cease by adolescence. Before our study:
- The prevalence of sleep terrors in childhood was estimated to be between 1% and 6.5% (1,2).
- In adults, the prevalence of sleep terrors was unknown.
Studies in clinical populations have found sleep terrors and mental disorders to be associated (1,3).

METHODS

The purpose of the present study was twofold:

• to investigate the prevalence of sleep terrors in a general population;
• to identify factors associated with sleep terrors.

We used a representative sample of the UK population (N=4972) that was interviewed by telephone with the Sleep-EVAL system.

RESULTS

Sleep terrors were reported by 2.2% (95% Confidence Intervals: 1.8% to 2.6%) of the sample.

It decreased significantly with age, but no gender difference was observed.

Multivariate models identified the following independent factors as associated with sleep terrors:

• subjective sense of choking or blocked breathing at night (Odds ratio (OR): 5.1),
• obstructive sleep apnea syndrome (OR: 4.1),
• alcohol consumption at bedtime (OR: 3.9),
• violent or injury-causing behaviours during sleep (OR: 3.2),
• hypnagogic hallucinations (OR: 2.2), and
• nightmares at least one night per month (OR: 4.0).

In our survey:

• The sleep terrors group had the highest rates of current and past mood and anxiety disorders.
• The fact that sleep terrors were found to be associated with obstructive sleep apnea, the subjective sense of choking or blocked breathing at night (a symptom of sleep-choking syndrome), and panic disorder suggests that some of these subjects may suffer from nocturnal panic attacks.
• This disorder can produce symptoms like sleep terrors.

A careful examination of the symptoms accompanying the episodes is necessary to distinguish these disorders:
- Nocturnal panic attacks are normally characterized by various physiological signs, such as change in heart beat and breathing;
- Sleep terrors occur suddenly without forewarning. Furthermore, subjects suffering from sleep terrors usually do not have daytime panic attacks or agoraphobia symptoms.

Similarly, sleep-choking syndrome, which is characterized by sudden awakenings with the feeling of being unable to breath, is accompanied by an intense anxiety and often a sense of dying.

Unlike persons with sleep terrors, subjects suffering from sleep-choking syndrome are immediately fully awake and their fears recede rapidly.

Distinguishing sleep-choking syndrome from sleep apnea syndrome is more problematic, as sleep monitoring is normally required to confirm the latter.

The relationship between psychopathology and sleep terrors is not entirely clear.

The course of these two conditions presents little or no overlapping, which suggests the existence of other unidentified underlying factors that would predispose some adults to sleep terrors and mental disorders.

The association between sleep terrors and violent or injury-causing behaviours occurring during sleep must be brought to the forefront, given the general assumption that sleep terrors are harmless.

REFERENCES