Elisa Morrone

Periodic limb movements both in non-REM and REM sleep: Relationships between cerebral and autonomic activities

OBJECTIVE To investigate the temporal relationship between cerebral and autonomic activities before and during periodic limb movements in NREM and REM sleep (PLMS). METHODS Patterns of EEG, cardiac and muscle activities associated with PLMS were drawn from polysomnographic recordings of 14 outpatients selected for the presence of PLMS both in NREM and REM sleep. PLMS were scored during all sleep stages from tibial EMG. Data from a bipolar EEG channel were analyzed by wavelet transform. Heart rate (HR) was evaluated from the electrocardiogram. EEG, HR and EMG activations were detected as transient increase of signal parameters and examined by analysis of variance and correlation analysis independently in NREM and REM sleep. Homologous parameters in REM and NREM sleep were compared by paired t-test. RESULTS The autonomic component, expressed by HR increase, took place before the motor phenomenon both in REM and NREM sleep, but it was significantly earlier during NREM. In NREM sleep, PLM onset was heralded by a significant activation of delta-EEG, followed by a progressive increase of all the other bands. No significant activations of delta EEG were found in REM sleep. HR and EEG activations positively correlated with high frequency EEG activations and negatively (in NREM) with slow frequency ones. CONCLUSIONS Our findings suggested a heralding role for delta band only in NREM sleep and for HR during both NREM and REM sleep. Differences in EEG and HR activation between REM and NREM sleep and correlative data suggested a different modulation of the global arousal response. SIGNIFICANCE In this study, time-frequency analysis and advanced statistical methods enabled an accurate comparison between brain and autonomic changes associated to PLM in NREM and REM sleep providing indications about interaction between autonomic and slow and fast EEG components of arousal response.

Activation of the motor cortex during phasic rapid eye movement sleep

When dreaming during rapid eye movement (REM) sleep, we can perform complex motor behaviors while remaining motionless. How the motor cortex behaves during this state remains unknown. Here, using intracerebral electrodes sampling the human motor cortex in pharmacoresistant epileptic patients, we report a pattern of electroencephalographic activation during REM sleep similar to that observed during the performance of a voluntary movement during wakefulness. This pattern is present during phasic REM sleep but not during tonic REM sleep, the latter resembling relaxed wakefulness. This finding may help clarify certain phenomenological aspects observed in REM sleep behavior disorder. Ann Neurol 2016;79:326–330

Circadian sleep propensity and alcohol interaction at the wheel

STUDY OBJECTIVES The study was aimed at estimating the effect of alcohol consumption, time of day, and their interaction on traffic crashes in a real regional context. METHODS Blood alcohol concentration (BAC) data were collected from drivers involved in traffic accidents during one year in an Italian region and in a control group of drivers over the same road network. Mean circadian sleep propensity was estimated from a previous study as function of time of day. Accident risk was analyzed by logistic regression as function of BAC and circadian sleep propensity. RESULTS BAC values greater than zero were found in 72.0% of the drivers involved in crashes and in 40.4% of the controls. Among the former 23.6% of the drivers exceeded the BAC legal threshold of 0.05 g/dL, while illegal values were found in 10.4% of the controls. The relative risk showed a significant increase with both BAC and circadian sleep propensity (as estimated from time of day) and their interaction was significant. CONCLUSIONS Due to the significant interaction, even low BAC levels strongly increased accident risk when associated with high sleep propensity.

Development and validation of the Maugeri Sleep Quality and Distress Inventory (MaSQuDI-17)

Objectives The aim of this study was to develop and validate a questionnaire designed to measure the impact of sleep impairment on emotional distress in patients with various sleep disorders. Methods Five experts created an item data-bank pertaining to sleep-related psychological symptoms and somatic perceptions. Fifty patients in two focus groups examined each item for: a) word clarity (indicating any ambiguity of interpretation) and b) appropriateness for the target population. This process permitted to identify 36 appropriate items. Classical Test Theory and Rasch Analysis were used to further refine the questionnaire, yielding the final 17-item set. Concurrent validation of the new scale was tested with the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and the Anxiety and Depression questionnaires. Results Starting from the initial item data-bank, a 17-item questionnaire, the Maugeri Sleep Quality and Distress Inventory (MaSQuDI–17), was produced. Parallel Analysis on the MaSQuDI–17 confirmed the presence of a single dimension; exploratory factor analysis showed salient loading for each item, explaining 58.7% of total variance. Item-remainder correlation ranged from 0.72 to 0.39 and Cronbach alpha was 0.896. Rasch analysis revealed satisfactory psychometric properties of the new scale: the rating structure performed according to expectations, model fit was good and no item dependencies emerged. The scale presented good convergent validity and scores significantly distinguished healthy subjects from OSAS or Insomnia or BSD (p < 0.001). Conclusions MaSQuDI –17 shows good psychometric qualities, and can be used to assess the impact of sleep disorders such as Insomnia, OSAS, Central Hypersomnia and BSD on emotional stress.