The nonrapid eye movement parasomnias: recent advances and forensic aspects.

PURPOSE OF REVIEW: The aim is to update the readership on recent advances in the diagnosis and classification of nonrapid eye movement (NREM) sleep parasomnias with an emphasis on recent research findings and related forensic consequences of the parasomnias. RECENT FINDINGS: The Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) has further refined the classification and diagnostic criteria for the parasomnias, dividing them into non-REM and REM sleep disorders. It has removed confusional arousal disorder and updated the diagnostic criteria in keeping with the evidence-base available at the time of its final drafting. New research subsequent to the final drafting of the DSM-5 has clarified certain aspects including those related to the risk factors ('triggers') for sleepwalking and the impact of sleepwalking on daytime functioning, social and occupational functioning. These new research data should be considered in the development of the next International Classification of Sleep Disorders. The new diagnostic system and research data provide further clarity for the forensic sleep medicine practitioner. SUMMARY: The DSM-5 diagnostic criteria combined with the latest research will inform both clinical and forensic sleep medicine practice and provide further impetus for evidence-based practice.

Alcohol and sleep I: effects on normal sleep.

This review provides a qualitative assessment of all known scientific studies on the impact of alcohol ingestion on nocturnal sleep in healthy volunteers. At all dosages, alcohol causes a reduction in sleep onset latency, a more consolidated first half sleep and an increase in sleep disruption in the second half of sleep. The effects on rapid eye movement (REM) sleep in the first half of sleep appear to be dose related with low and moderate doses showing no clear trend on REM sleep in the first half of the night whereas at high doses, REM sleep reduction in the first part of sleep is significant. Total night REM sleep percentage is decreased in the majority of studies at moderate and high doses with no clear trend apparent at low doses. The onset of the first REM sleep period is significantly delayed at all doses and appears to be the most recognizable effect of alcohol on REM sleep followed by the reduction in total night REM sleep. The majority of studies, across dose, age and gender, confirm an increase in slow wave sleep (SWS) in the first half of the night relative to baseline values. The impact of alcohol on SWS in the first half of night appears to be more robust than the effect on REM sleep and does not appear to be an epiphenomenon REM sleep reduction. Total night SWS is increased at high alcohol doses across gender and age groups.

Sleep stage sequence analysis of sleep onset REM periods in the hypersomnias.

BACKGROUND: The Multiple Sleep Latency Test (MSLT) remains an important diagnostic tool in the diagnosis of hypersomnias. However, a positive MSLT may be found in other sleep disorders, such as behaviourally induced inadequate sleep syndrome (BIISS). It has been demonstrated that in sleep onset rapid eye movement (SOREM) periods in BIISS, REM sleep tends to arise from stage 2 sleep (non-REM (NREM) 2), rather than stage 1 sleep (NREM1), as in narcolepsy. METHODS: We performed sleep stage sequence analysis on 127 patients with nocturnal polysomnography and MSLT, including 25 with narcolepsy with cataplexy (N+C), 41 with narcolepsy without cataplexy (N-C), 21 with idiopathic hypersomnia with long sleep time (IHL), 20 with BIISS and 20 with periodic limb movement disorder (PLMD). 537 naps were recorded, containing 176 SOREM periods. RESULTS: All SOREM periods in the IHL, BIISS and PLMD groups arose from NREM2 sleep, 75% of those in N+C arose from NREM1 and in N-C only 52% arose from NREM1. Within the N-C group, those with SOREM periods all arising from stage 1 had a shorter MSL (p=0.02). CONCLUSIONS: These results suggest that SOREM periods arising from NREM1 have high sensitivity for the diagnosis of narcolepsy and that SOREM periods from NREM1 are a marker of severity, either of sleepiness or REM instability. Sleep stage sequence analysis of SOREM periods may also aid more accurate phenotyping of the hypersomnias and in particular clarify heterogeneity among patients with narcolepsy without cataplexy.