Non-rapid eye movement sleep

About: Non-rapid eye movement sleep is a research topic. Over the lifetime, 8661 publications have been published within this topic receiving 389465 citations. The topic is also known as: NREM.

Two distinct synchronization processes in the transition to sleep: a high-density electroencephalographic study.

Abstract: Objectives To assess how the characteristics of slow waves and spindles change in the falling-asleep process. Design Participants undergoing overnight high-density electroencephalographic recordings were awakened at 15- to 30-min intervals. One hundred forty-one falling-asleep periods were analyzed at the scalp and source level. Setting Sleep laboratory. Participants Six healthy participants. Interventions Serial awakenings. Results The number and amplitude of slow waves followed two dissociated, intersecting courses during the transition to sleep: slow wave number increased slowly at the beginning and rapidly at the end of the falling-asleep period, whereas amplitude at first increased rapidly and then decreased linearly. Most slow waves occurring early in the transition to sleep had a large amplitude, a steep slope, involved broad regions of the cortex, predominated over frontomedial regions, and preferentially originated from the sensorimotor and the posteromedial parietal cortex. Most slow waves occurring later had a smaller amplitude and slope, involved more circumscribed parts of the cortex, and had more evenly distributed origins. Spindles were initially sparse, fast, and involved few cortical regions, then became more numerous and slower, and involved more areas. Conclusions Our results provide evidence for two types of slow waves, which follow dissociated temporal courses in the transition to sleep and have distinct cortical origins and distributions. We hypothesize that these two types of slow waves result from two distinct synchronization processes: (1) a "bottom-up," subcorticocortical, arousal system-dependent process that predominates in the early phase and leads to type I slow waves, and (2) a "horizontal," corticocortical synchronization process that predominates in the late phase and leads to type II slow waves. The dissociation between these two synchronization processes in time and space suggests that they may be differentially affected by experimental manipulations and sleep disorders.

The association between daytime sleepiness and sleep-disordered breathing in NREM and REM sleep.

Abstract: SLEEP-DISORDERED BREATHING IS CHARACTERIZEDBY REPETITIVE EPISODES OF PARTIAL OR COMPLETECOLLAPSE OF THE UPPER AIRWAY DURING SLEEP. Theresulting decrease or cessation in airflow is often associated withoxyhemoglobin desaturation and/or an arousal from sleep. Inpatients with sleep-disordered breathing, respiratory events mayoccur throughout non-rapid eye movement (NREM) and rapideye movement (REM) sleep. The typical finding is that respira-tory events during REM sleep are longer and are associated witha greater degree of hypoxemia than events that occur duringNREM sleep. These characteristics may be related to the markeddifferences in arousal responses to respiratory stimuli (i.e.,hypoxemia and hypercapnia) between REM and NREM sleep.In general, greater stimulus intensities are required to elicit anarousal from REM than NREM sleep.

Sleep and Dreaming: The case against memory consolidation in REM sleep

Abstract: We present evidence disputing the hypothesis that memories are processed or consolidated in REM sleep. A review of REM deprivation (REMD) studies in animals shows these reports to be about equally divided in showing that REMD does, or does not, disrupt learning/memory. The studies supporting a relationship between REM sleep and memory have been strongly criticized for the confounding effects of very stressful REM deprivation techniques. The three major classes of antidepressant drugs, monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), and selective serotonin reuptake inhibitors (SSRIs), profoundly suppress REM sleep. The MAOIs virtually abolish REM sleep, and the TCAs and SSRIs have been shown to produce immediate (40-85%) and sustained (30-50%) reductions in REM sleep. Despite marked suppression of REM sleep, these classes of antidepressants on the whole do not disrupt learning/memory. There have been a few reports of patients who have survived bilateral lesions of the pons with few lingering complications. Although these lesions essentially abolished REM sleep, the patients reportedly led normal lives. Recent functional imaging studies in humans have revealed patterns of brain activity in REM sleep that are consistent with dream processes but not with memory consolidation. We propose that the primary function of REM sleep is to provide periodic endogenous stimulation to the brain which serves to maintain requisite levels of central nervous system (CNS) activity throughout sleep. REM is the mechanism used by the brain to promote recovery from sleep. We believe that the cumulative evidence indicates that REM sleep serves no role in the processing or consolidation of memory.