Disorders of Arousal and Sleep-Related Behaviors

Disorders of arousal constitute a spectrum of non-rapid eye movement (NREM) parasomnias in which incomplete transitions between sleep stages give rise to complex motor and behavioural phenomena. Manifestations include confusional arousals, sleep terrors and sleepwalking, often accompanied by gestural enactments, vocalisations or even violence. Episodes typically occur during slow-wave sleep and are characterised by limited awareness, variable recall and disrupted sleep architecture. Predisposing factors encompass genetic susceptibility, stress, sleep deprivation and concurrent sleep disorders such as obstructive sleep apnoea or periodic limb movements. Advances in neurophysiology have revealed that parasomnia behaviours emerge from local dissociations of cortical and subcortical activity, with slow electroencephalographic oscillations coexisting alongside wake-like regional activation. Clinically, disorders of arousal pose challenges in diagnosis and management owing to their variable semiology and potential for injury or legal implications. Standard assessment integrates detailed history, overnight physiological monitoring and, when indicated, video-polysomnography. Emerging insights into the neural mechanisms of sleep consciousness and motor control promise to refine diagnostic criteria and inform targeted interventions worldwide.

Research from Nature Portfolio

Recent studies employing high-density electroencephalography have elucidated the neural correlates of conscious and unconscious parasomnia experiences. Analyses of parasomnia episodes recorded in laboratory settings reveal that episodes accompanied by subjective reports of dreaming are preceded by prominent slow waves in anterior cortical regions and concurrent activation of posterior networks. Moreover, successful recall of dream content correlates with enhanced activation in medial temporal structures prior to motor onset. These findings suggest that the physiological substrates underlying dreaming and parasomnia enactment overlap substantially, indicating a shared mechanism for sleep consciousness across both normal and disordered states.

Disorders of Arousal and Sleep-Related Behaviors publication trend

The graph below shows the total number of articles in disorders of arousal and sleep-related behaviors across all publications each year (not limited to Nature Index journals).

Technical terms

Parasomnia: An undesirable motor, behavioural or experiential phenomenon occurring during sleep or transitions between sleep and wakefulness.

Non-rapid eye movement (NREM) sleep: Sleep stages characterised by slow-wave electroencephalographic activity and absence of rapid eye movements, subdivided into light and deep phases.

Arousal: A transient shift from deeper to lighter stages of sleep or to full wakefulness, often associated with cortical activation and autonomic changes.

Electroencephalography (EEG): A non-invasive technique for recording electrical activity of the brain via electrodes placed on the scalp, used to identify sleep stages and cortical oscillations.

Video-polysomnography (VPSG): A comprehensive sleep study combining simultaneous video recording with multi-channel physiological monitoring to capture behavioural and electrophysiological data.

References

1. Shared EEG correlates between non-REM parasomnia experiences and dreams. Nature Communications (2024).
2. Conscious experiences during non-rapid eye movement sleep parasomnias. Neuroscience & Biobehavioral Reviews (2024).
3. Clinical Features and Pathophysiology of Disorders of Arousal in Adults: A Window Into the Sleeping Brain. Frontiers in Neurology (2019).
4. Video polysomnographic findings in non‐rapid eye movement parasomnia. Journal of Sleep Research (2018).
5. NREM parasomnias: a treatment approach based upon a retrospective case series of 512 patients. Sleep Medicine (2018).