Clinical manifestations

Presentation and course

Sleeptalking consists of utterances that occur during the sleep episode. The episodes may occur during REM or NREM sleep or during arousals. Sleeptalking is not related to time of night; nearly 20% occurs during REM, whereas 80% is NREM associated, approximately matching the time spent in each sleep stage (25). Some subjects speak either from REM or NREM only, but some speak from both.

Sleeptalking occurs accompanied by alpha activity superimposed on EEG activity, typical for the stage giving rise to the utterance (36). The utterances may be brief, infrequent, and devoid of any emotional stress, or they may include long speeches and hostile or angry outbursts up to over 100 words, although typical duration is a few seconds. The content of speech may reflect that of simultaneously occurring nondream or dream mentation, but the vocalizations are usually difficult to understand and are frequently nonsensical. Sleeptalking can sometimes be induced by conversation with a predisposed sleeping individual. Episodes occurring during REM sleep may be more often associated with recall of sleep mentation.

Prognosis and complications

Sleeptalking is typically a benign condition that resolves spontaneously. Sleeptalking may last for a few nights, several months, or years. Apart from annoyance for the bed partner, no other complications are present (10). In adults, psychiatric disorders are twice as common in frequent sleeptalkers (23). A special warning should be considered on sedative drugs, especially GABA-A agonists (13), which are known to increase sleeptalking frequency and duration.

Clinical vignette

Case 1. A 59-year-old man with REM sleep behavior disorder (RBD) shouted, "You bastard, I’ll put your lights out!” just before jumping out of bed and hitting an invisible enemy he’d been dreaming about. This patient had been recently diagnosed with Parkinson disease and was evaluated in a sleep laboratory for an ongoing history of violent, nocturnal, self-injurious behavior occurring several times per month and starting 5 years prior to the diagnosis of Parkinson disease. His verbal utterance occurred in the context of an episode of REM sleep without atonia and was accompanied by phasic EMG bursts recorded from all 4 limbs. On awakening, the patient was able to report a congruous dream, but had no recollection of his screaming.

Case 2. Matthew, a 16-year-old adolescent, reported that his 8-year-old brother, David, often spoke in his sleep and would wake him up, 2 to 3 hours following sleep onset, by uttering mostly unintelligible words generally referring to a movie he had been watching or a video game he had been playing prior to bedtime. The length of these episodes varied from 1 to 2 minutes to 10 to 15 minutes and occurred as often as twice a week, subsiding for longer intervals in the summer. These episodes were proved to occur during non-REM sleep. No specific treatment was deemed necessary.

Biological basis

Etiology and pathogenesis

Sleeptalking is sometimes associated with sleep loss, stress, psychopathology, or medical illness with fever. An anecdotal report exists concerning sleeptalking and pathological laughter association with clival chordoma (30). Sleep talking and delirium were reported as presenting symptoms of Hashimoto encephalopathy in a female patient with antithyroid peroxidase antibodies (TPO-Ab) in her CSF with EEG frontal slowing showing brain MRI abnormalities at the level of the commissural magna cerebri. A 3-day intravenous methylprednisolone (500 mg/day) treatment was able to promptly revert symptoms (22). Sleeptalking is a common finding in patients with Parkinson disease (44). In a study of 12 patients with Parkinson disease who screamed during sleep, sleeptalking was in several cases retrospectively identified to have preceded the onset of Parkinson disease (32). A paper reports increased frequency of nocturnal vocalization in patients with pure autonomic failure compared to idiopathic Parkinson disease and dementia with Lewy bodies, suggesting that dream enactment typical of REM sleep behavior disorder is equally shared by these disorders despite the absence of motor symptoms and dopaminergic involvement in pure autonomic failure (26). The same extent of brainstem lesions critical to REM sleep behavior disorder probably exists in all conditions, with Lewy bodies seen in pure autonomic failure, idiopathic Parkinson disease, and dementia with Lewy bodies (14).

Sleeptalking has been described in the context of IgLON5 (39) with a prevalence greater than 80%. In particular, N2 is characterized in this syndrome as poorly structured with frequent reports of sleep mumbling, vocalizations, laughing, and crying.

In this context, but also in the general population, sleeptalking is often precipitated by episodes of apneas or sleep disordered breathing. Gaig and colleagues describe simple and complex vocalizations and movements elicited by termination of apnea episodes, mostly in NREM sleep, rarely in REM (18). The condition tends to endure into adult life with persistent obstructive sleep apnea.

In an experimental protocol, Uguccioni and colleagues assessed declarative verbal learning in REM behavior disorder patients versus control subjects (40). Nighttime verbal consolidation was normal in REM behavior disorder patients unlike daytime consolidation, with incorporation of learned material with REM sleep talking in 1 out of 18 patients. Sleeptalking has also been described as part of NREM parasomniac behaviors (NPBs) in Parkinson disease and multiple system atrophy patients. More specifically elementary NREM parasomniac behaviors consisted of lingering, talking, and purposeless slow movements, whereas confusional NREM parasomniac behaviors, only typical of Parkinson disease patients, represented orienting responses often accompanied by vocalization as if calling out to someone. Most of these behaviors were triggered by respiratory events. NREM parasomniac behaviors are thought to be accounted for by primitively abnormal prefrontal and frontal networks in Parkinson disease or to be a consequence of dopaminergic agents used by these patients.

Sleeptalking has been associated with atypical sexual behavior during sleep, or sleep-related eating disorder, or both (29), during confusional arousals or sleep walking episodes.

Only in adults, it is more often associated with psychological or psychiatric abnormalities (23). The content of the sleeptalking should be taken lightly. Subjects sleeptalk in any of their dominant languages; however, immediate past events seem to influence the language used (41).

An interesting analysis and classification of sleeptalking content in terms of brain state has been published on account of Dion McGregor’s sleeptalking episodes (06). Dion McGregor (born in 1922) was the most extensive sleeptalker ever recorded. By using the Hall and van de Castle Content Scales typically applied to analyze dreams, the authors compared sleeptalking episodes from McGregor to normative male dreams (19; 21). By doing so, they found fewer female characters, but more familiar characters and friends, and less aggression, friendliness, or sex per character, but significantly more self-negativity in McGregor’s narratives, according to the Hall and van de Castle scale. As for bizarreness (Hobson’s scale), no differences were found between sleeptalking and dreams in 3 out of 6 scales, as far as discontinuity, but less incongruity of characters, objects, and actions and fewer incongruities or uncertainty of thoughts. The authors tried to explain these results as due to the differences in frontal activation in the 2 different states: sleeptalking and dreaming (33). In fact, the decreased bizarreness in sleeptalking is congruous with the known sleeptalking physiology in terms of partial reactivation of the dorsolateral prefrontal cortex (DLPC) due to increased alpha preceding the central sleeptalking episode. Furthermore, the increased activity of the subject (McGregor) in the sleeptalking episodes as a befriender or aggressor is likely related to his state (self-agency) with an EEG closer to waking, against the passivity of dreaming.

According to Alfonsi and colleagues, sleeptalking reflecting ongoing dream content may represent a unique possibility to directly access mental experience during sleep (02).

REM sleep-associated sleeptalking correlates with dream recall frequency as a function of specific neurophysiologic patterns of activation (12). A specific coherence of somniloquy with the subject’s affective tone has been reported. In this sense, rather than “acting out” dreams as in REM behavior disorder, sleeptalking could be seen as a sort of “speaking out” dreams (02).

As far as psycholinguistic processes are concerned, sleeptalking provides a unique opportunity to examine local arousals in specific linguistic circuits activated in the sleeping brain. Arnulf and colleagues showed that syntactic and prosody rules of conversation seem to be preserved during sleep even if the phonatory system appears to be inhibited, as if independent from attention-demanding processes (04). It remains to be seen whether these recruited higher cerebral areas are the same in different sleep stages or in terms of clinical relevance in disorders of arousals vs REM behavior disorder.

Sleeptalking should also be explored in relation to the hypothesis of memory activation of newly acquired information during sleep. Neuronal replay of recent memories in slow wave sleep with song replay in birds learning to sing has been demonstrated in experimental animal studies (11). Brain imaging and electroencephalographic studies in humans also support the sleep learning-dependent hypothesis (31; 34).

Epidemiology

A cross sectional epidemiologic study of adults older than 18 years of age from Norway assessed a lifetime prevalence of 66% for sleeptalking, with a prevalence of 17% in the 3 months prior to the survey (08). Prevalence of sleeptalking is at least once a year in about 50% of children (42). The prevalence in different studies is influenced by environmental and cultural features involving varying homes and sleeping practices. Co-sleeping or crowding, in fact, appear to increase sleeptalking frequency (28).

Sleeptalking is common, although loud sleeptalking that is annoying to others may be rare. It occurs more often in children than in adults (only 5%). However, the prevalence of sleeptalking shows no clear dependence on age or sex in large populations of children (37; 17). In adults, sleeptalking seems to be a common trait in both genders (02).

One half of children between 3 and 10 years of age sleeptalk at least once a year, and approximately 10% sleeptalk on a nightly basis (37). The overall prevalence of parent-reported symptoms of sleeptalking in an epidemiologic survey among children 2 to 12 years old in Beijing, China was 4.9% (28). Similar prevalences are reported in primary school children all over China: 4.8% in Urumqi (01) and 5.5% in Chagsha (09); a higher prevalence of 14.6% was reported in India in children aged 3 to 10 years (07). Sleepwalking, nightmares, and sleeptalking in children are strongly associated with each other (27). Nocturnal enuresis seems to be unrelated to sleeptalking.

Children are more likely to sleeptalk if 1 or both parents have a parasomnia such as sleepwalking (41). A significant increase in nocturnal muscle cramps, bed wetting, colic, drooling when sleeping, and sleeptalking occurs among bruxers compared to controls (43; 38). Also, long term habitual snorers were at significantly increased risk for sleeptalking with hypnic jerks and bruxism (OR 12.3: 8-37.3 CI 95%) in addition to excessive daytime sleepiness and behavioral problems (16). Sleep talking was increased as well as bruxism, leg movements, nightmares, and sleep disordered breathing in a vast sample of children with headache compared to controls (45).

Sleeptalking has a clear genetic influence. In a twin study of parasomnias, the strongest genetic covariation was found in sleeptalking with sleepwalking, sleeptalking with bruxism, and in sleeptalking with nightmares. Based on the co-occurrence in monozygotic twins and dizygotic twins, the estimated proportions of shared genetic effects were 50%, 30%, and 26%, respectively (24). However, no candidate genes are present.

Secondary sleeptalking is associated with a panoply of sleep disorders/nighttime conditions, with different prevalence depending on subject’s age and severity and duration of the underlying condition (25). The latter include:

Disorders of Arousal

Confusional arousals Night terrors Sleep walking Sleep related eating disorder Sexsomina REM Parasomnia REM behavior disorder Parasomnia overlap disorder Agripnia Excitata Status Dissociatus IgLON5 Nocturnal Frontal Lobe Epilepsy Other sleep disorders Period limb movements disorder Restless Legs Syndrome Obstructive Sleep Apnea Nocturnal Panic Attacks

Prevention

Avoidance of emotional stress and sleep deprivation may be helpful.

Differential diagnosis

Sleeptalking should be differentiated from periods of talking during nocturnal awakenings. Sleeptalking can also occur in other sleep disorders, such as obstructive sleep apnea, REM sleep behavior disorder, sleep terrors, confusional arousals, and sleepwalking. Vocalizations are often described during nocturnal seizures and in posttraumatic stress disorder; they may be mixed with the grunting expiratory sound in prolonged episodes of catathrenia (15).

Diagnostic workup

Usually, isolated sleeptalking does not require any diagnostic workup. If features of other sleep disorders, such as obstructive sleep apnea syndrome or REM sleep behavior disorder are present, further workup including polysomnographic documentation may be needed. This is the case also for REM- and NREM-related behaviors in Parkinson disease and multiple system atrophy (35)

Management

No specific treatment for sleeptalking exists, although attention to sleep hygiene (25) and treatment of an underlying disorder that precipitates the sleeptalking is usually helpful. Reassurance to parents and caregivers is also recommended.

Special considerations

Pregnancy

In a Finnish population of pregnant women, sleeptalking decreased significantly from the prepregnant period to the second trimester for 23% to 13% of women. As a matter of fact, the reported frequency of all parasomnias, except sleep paralysis, decreases during pregnancy. The changes were more pronounced in primiparas than multiparas (20).

Anesthesia

Sleeptalkers usually increase this behavior while recovering from general anesthesia.