Hypersynchronous delta sleep EEG activity and sudden arousals from slow-wave sleep in adults without a history of parasomnias: clinical and forensic implications

Sleep. 2004 Jun 15;27(4):706-10. doi: 10.1093/sleep/27.4.706.


Study objectives: To determine the frequency of classical markers of non-rapid eye movement (NREM) parasomnias--hypersynchronous delta sleep (HSD) electroencephalogram waves and sudden arousals from slow-wave sleep (SWS)--in patients without histories of somnambulism or other NREM parasomnias.

Design: Retrospective review.

Setting: Sleep disorders center laboratory.

Patients: 82 consecutive patients without a history of parasomnias who underwent diagnostic polysomnograms; 57 men and 25 women, mean age 48+/-13.3 years, were included without regard to diagnosis or findings. All patients had at least 30 seconds of stage 3 or 4 sleep during the polysomnogram.

Measurements and results: The primary diagnosis of all but 4 patients was obstructive sleep apnea (mean respiratory disturbance index, 30 +/- 23.6 [range, 2.7-117] per hour of sleep). Polysomnograms were then reviewed for the presence of HSD and SWS arousals. A total of 235 arousals (mean, 2.9 +/- 2.7; range, 0-14) from stage 3 or 4 sleep were noted. Eight-five percent of all patients had at least 1 SWS arousal and 45% had 3 or more SWS arousals; 85.1% of all arousals from SWS were secondary to sleep-disordered breathing, and 5.9% were secondary to leg movements. At least 1 episode of HSD (mean, 1.4 +/- 1.6; range, 0-9) was noted in 65.8% of patients.

Conclusions: HSD and SWS arousals were a common finding in patients without clinical histories of sleepwalking or other parasomnias but who were found to have frequent respiratory-related arousals during sleep. HSD and SWS arousals thus have a low specificity for NREM parasomnias and, without further research, are not useful for the objective confirmation of parasomnias in clinical evaluations and in the forensic evaluation of sleepwalking as a legal defense.

MeSH terms

  • Arousal / physiology*
  • Cortical Synchronization / instrumentation
  • Delta Rhythm*
  • Electroencephalography
  • Electromyography
  • Female
  • Forensic Psychiatry*
  • Humans
  • Male
  • Middle Aged
  • Polysomnography
  • Retrospective Studies
  • Sleep / physiology*
  • Sleep Apnea Syndromes / diagnosis