An Asymmetrical Hypothesis for the NREM-REM Sleep Alternation-What Is the NREM-REM Cycle?

Since the discovery of rapid eye movement (REM) sleep (Aserinsky and Kleitman, 1953), sleep has been described as a succession of cycles of non-REM (NREM) and REM sleep episodes. The hypothesis of short-term REM sleep homeostasis, which is currently the basis of most credible theories on sleep regulation, is built upon a positive correlation between the duration of a REM sleep episode and the duration of the interval until the next REM sleep episode (inter-REM interval): the duration of REM sleep would therefore predict the duration of this interval. However, the high variability of inter-REM intervals, especially in polyphasic sleep, argues against a simple oscillator model.

Psychophysical evaluation of chemosensory functions 5 weeks after olfactory loss due to COVID-19: a prospective cohort study on 72 patients.

Purpose: To evaluate the evolution of chemosensation via extended psychophysical testing in patients who suffered from sudden chemosensory loss due to coronavirus disease 2019 (COVID-19). Additionally, this study sought to determine whether odor threshold testing provided additional information on olfactory loss due to COVID-19 compared to the more common odor identification testing.

Methods: Prospective cohort study of patients with sudden chemosensory loss since February 2020 and confirmed COVID-19 infection via RT-PCR or serology testing.

Relationships between REM and NREM in the NREM-REM sleep cycle: a review on competing concepts.

Sixty-five years after the discovery of rapid eye movement (REM) sleep, the reasons why we sleep and why we need two states of sleep are still largely unclear. Moreover, the functional relationship between the two types of sleep remains the matter of much conjecture. Several questions come to mind.

Sleep ultradian cycling: Statistical distribution and links with other sleep variables, depression, insomnia and sleepiness-A retrospective study on 2,312 polysomnograms.

The number of alternations between Non-Rapid Eye Movement (NREM) sleep and Rapid Eye Movement (REM) sleep in humans is usually considered to consist of 4-5 cycles of about 90 minutes duration per night. Previous studies by our group showed a normal distribution on 26 healthy human subjects. The present study retrospectively analyzes the polysomnograms of 2,312 unmedicated patients who were admitted for medical and/or psychiatric reasons in the Erasme University Hospital between 2003 and 2014.

Usefulness of a multiplying factor in predicting the final number of victims during a mass casualty incident.

Objective: Whenever a mass casualty incident (MCI) occurs, it is essential to anticipate the final number of victims to dispatch the adequate number of ambulances. In France, the custom is to multiply the initial number of prehospital victims by 2-4 to predict the final number. However, no one has yet validated this multiplying factor (MF) as a predictive tool.

[On the benefits to keep using the asperger diagnosis].

The purpose of this paper is to examine the possible benefits to keep using the diagnosis of Asperger's syndrome. We first describe the evolution of this entity over time and within nomenclature bases such as the ICD- 10, the CFTMEA and the last versions of DSM. Then, we discuss more precisely the impact of the decision made in the DSM-5 to suppress the Asperger syndrome as a differentiated entity within the pervasive developmental disorders (PDD).

Slow wave sleep in the chronically fatigued: Power spectra distribution patterns in chronic fatigue syndrome and primary insomnia.

Objectives: To investigate slow wave sleep (SWS) spectral power proportions in distinct clinical conditions sharing non-restorative sleep and fatigue complaints without excessive daytime sleepiness (EDS), namely the chronic fatigue syndrome (CFS) and primary insomnia (PI). Impaired sleep homeostasis has been suspected in both CFS and PI.

Methods: We compared perceived sleep quality, fatigue and sleepiness symptom-intensities, polysomnography (PSG) and SWS spectral power distributions of drug-free CFS and PI patients without comorbid sleep or mental disorders, with a good sleeper control group.

Age distribution curve in psychiatric admissions inversely correlates with Life Satisfaction.

A strong inverse correlation was found between the age-distribution curve of psychiatric admissions and the U-bend Life Satisfaction curve. It may indicate that the peak of mental disorders at midlife reflects a less satisfactory period of life or, conversely, that the mental health load burdens of Life Satisfaction.

Dimensions of pure chronic fatigue: psychophysical, cognitive and biological correlates in the chronic fatigue syndrome.

Objectives: To investigate associated dimensions of fatigue regarding cognitive impairment, psychomotor performances, muscular effort power and circulating cytokine levels and their relations to symptom intensity in a sample of pure chronic fatigue syndrome (CFS) patients without overlapping objective sleepiness or sleep disorders.

Methods: 16 CFS patients were compared to 14 matched controls. We assessed structured symptom-scales, polysomnography, multiple sleep latency tests, attention (Zazzo-Cancellation ZCT, digit-symbol-substitution DSST), psychomotor vigilance and speed (PVT, finger tapping test, FTT), dynamometer handgrip force (tonic and phasic trials) and circulating cytokines (IFN-γ, IL-1b, IL-6, IL-8, IL-10, TNF-α).

[Postpartum depression: correlations and predictive factors].

Post-partum depression (PPD) belongs to the depressive spectrum consecutive to a pregnancy. It is important to detect it as soon as possible to avoid non-negligible consequences for the mother, the new born and close relatives. It some cases, PPD may give way to post-partum psychosis, a psychiatric emergency.

Non-REM sleep EEG power distribution in fatigue and sleepiness.

Objectives: The aim of this study is to contribute to the sleep-related differentiation between daytime fatigue and sleepiness.

Methods: 135 subjects presenting with sleep apnea-hypopnea syndrome (SAHS, n=58) or chronic fatigue syndrome (CFS, n=52) with respective sleepiness or fatigue complaints and a control group (n=25) underwent polysomnography and psychometric assessments for fatigue, sleepiness, affective symptoms and perceived sleep quality. Sleep EEG spectral analysis for ultra slow, delta, theta, alpha, sigma and beta power bands was performed on frontal, central and occipital derivations.

Absence of systematic relationships between REMS duration episodes and spectral power Delta and Ultra-Slow bands in contiguous NREMS episodes in healthy humans.

Previous studies in animals and humans have reported correlations between the durations of rapid eye movement sleep (REMS) episodes and immediately preceding or subsequent non-REMS (NREMS) episodes. The relationship between these two types of sleep is a crucial component in understanding the regulation and neurophysiology of ultradian alternations that occur during sleep. Although the present study replicated previous studies, we also measured NREMS in terms of spectral power Delta and Ultra-Slow bands in addition to duration in examining correlations.

Ultra-slow delta power in chronic fatigue syndrome.

The role of sleep in patients diagnosed with chronic fatigue syndrome is not fully understood. Studies of polysomnographic and quantitative sleep electroencephalographic (EEG) measures have provided contradictory results, with few consistent findings in patients with Chronic Fatigue Syndrome (CFS). For the most part, it appears that delta EEG activity may provide the best discrimination between patients and healthy controls.

Neurocognitive determinants of novelty and sensation-seeking in individuals with alcoholism.

Aim: Sober alcoholic abusers exhibit personality traits such as novelty-seeking (NS) and sensation-seeking, which overlap to a limited extent. In parallel, they also show impaired executive and decision-making processes. However, little is known about the specific and common cognitive processes associated with NS and sensation-seeking personality traits in detoxified sober alcoholic abusers.

Cognitive impairment in fatigue and sleepiness associated conditions.

Although relating to very different concepts, sleepiness and fatigue are often confounded. However, both fatigue-associated conditions such as the chronic fatigue syndrome (CFS) and sleepiness-associated conditions such as the sleep apnea-hypopnea syndrome (SAHS) are associated with cognitive impairment with impaired attention, concentration and memory performances. Fifteen pure CFS patients, without primary sleep disorders or clinically relevant sleepiness, were compared to 15 untreated SAHS patients, without clinically relevant fatigue, and to 16 healthy controls of similar age.

Clinical complaints of daytime sleepiness and fatigue: how to distinguish and treat them, especially when they become 'excessive' or 'chronic'?

Chronic daytime fatigue and excessive daytime sleepiness (EDS) are potentially invalidating and also common complaints in primary care and general neurological practice. The lack of distinction in the clinical use of terms like fatigue and sleepiness is an important issue. Although these semiological concepts present fundamental differences from physiological and pathological points of view, general medical literature still often confuses both symptoms.

Do 'sleepy' and 'tired' go together? Rasch analysis of the relationships between sleepiness, fatigue and nonrestorative sleep complaints in a nonclinical population sample.

Objective: The lack of distinction in the clinical use of terms like fatigue and sleepiness is an important issue. While both fatigue and sleepiness can potentially be associated with nonrestorative sleep (NRS) complaints, their relationships are still poorly described. We propose to use Rasch analysis-based methods to study the interrelations of fatigue, sleepiness and NRS.

[Convulsions following dialysis sessions].

A bipolar patient with renal angiosclerosis due to lithium intoxication showed convulsive crises for about four months after each haemodialysis session. Aetiological work up was not able to isolate a unique cause, but modifications in treatment relieved the symptoms.