Contribution of REM sleep and N2 sleep spindles to procedural memory consolidation in Vipassana meditators and non-meditating controls.

Study objectives: Rapid eye movement (REM) sleep, non-rapid eye movement (NREM) sleep, and sleep spindles are all implicated in the consolidation of procedural memories. The relative contributions of sleep stages and sleep spindles was previously shown to depend on individual differences in task processing. Experience with Vipassana meditation is one such individual difference that has not been investigated in relation to sleep. Vipassana meditation is a form of mental training that enhances proprioceptive and somatic awareness and alters attentional style. The goal was thus to examine a potential moderating role for Vipassana meditation experience on sleep-dependent procedural memory consolidation.Methods: Groups of Vipassana meditation practitioners (N=20) and matched meditation-naïve controls (N=20) slept for a single daytime nap in the laboratory. Before and after the nap they completed a procedural task on the Wii Fit balance platform.Results: Meditators performed slightly better on the task before the nap, but the two groups improved similarly after sleep. The groups showed different patterns of sleep-dependent procedural memory consolidation: in meditators task learning was negatively correlated with density of fast and positively correlated with density of slow occipital spindles, while in controls task improvement was associated with increases in REM sleep. Meditation practitioners had a lower density of sleep spindles, especially in occipital regions.Conclusions: Results suggest that neuroplastic changes associated with sustained meditation practice may alter overall sleep architecture and reorganize sleep-dependent patterns of memory consolidation. The lower density of spindles in meditators may mean that meditation practice compensates for some of the memory functions of sleep.

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Nonrapid eye movement sleep electroencephalographic oscillations in idiopathic rapid eye movement sleep behavior disorder: a study of sleep spindles and slow oscillations

SLEEP ◽

10.1093/sleep/zsaa160 ◽

2020 ◽

Author(s):

Jun-Sang Sunwoo ◽

Kwang Su Cha ◽

Jung-Ick Byun ◽

Jin-Sun Jun ◽

Tae-Joon Kim ◽

...

Keyword(s):

Eye Movement ◽

Rem Sleep ◽

Rem Sleep Behavior Disorder ◽

Behavior Disorder ◽

Nrem Sleep ◽

Sleep Spindles ◽

Rapid Eye Movement ◽

Sleep Behavior ◽

Slow Oscillations ◽

Lower Amplitude

Abstract Study Objectives We investigated electroencephalographic (EEG) slow oscillations (SOs), sleep spindles (SSs), and their temporal coordination during nonrapid eye movement (NREM) sleep in patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD). Methods We analyzed 16 patients with video-polysomnography-confirmed iRBD (age, 65.4 ± 6.6 years; male, 87.5%) and 10 controls (age, 62.3 ± 7.5 years; male, 70%). SSs and SOs were automatically detected during stage N2 and N3. We analyzed their characteristics, including density, frequency, duration, and amplitude. We additionally identified SO-locked spindles and examined their phase distribution and phase locking with the corresponding SO. For inter-group comparisons, we used the independent samples t-test or Wilcoxon rank-sum test, as appropriate. Results The SOs of iRBD patients had significantly lower amplitude, longer duration (p = 0.005 for both), and shallower slope (p < 0.001) than those of controls. The SS power of iRBD patients was significantly lower than that of controls (p = 0.002), although spindle density did not differ significantly. Furthermore, SO-locked spindles of iRBD patients prematurely occurred during the down-to-up-state transition of SOs, whereas those of controls occurred at the up-state peak of SOs (p = 0.009). The phase of SO-locked spindles showed a positive correlation with delayed recall subscores (p = 0.005) but not with tonic or phasic electromyography activity during REM sleep. Conclusions In this study, we found abnormal EEG oscillations during NREM sleep in patients with iRBD. The impaired temporal coupling between SOs and SSs may reflect early neurodegenerative changes in iRBD.

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Don't count your chickens before they're hatched: Elaborative encoding in REM dreaming in face of the physiology of sleep stages

Behavioral and Brain Sciences ◽

10.1017/s0140525x1300126x ◽

2013 ◽

Vol 36 (6) ◽

pp. 613-614

Author(s):

Gaétane Deliens ◽

Sophie Schwartz ◽

Philippe Peigneux

Keyword(s):

Eye Movement ◽

Rem Sleep ◽

De Novo ◽

Nrem Sleep ◽

Sleep Stages ◽

Rapid Eye Movement ◽

Hidden Patterns ◽

Episodic Memories ◽

Novel Associations

AbstractLlewellyn suggests that episodic memories undergo “elaborative encoding” during rapid eye movement (REM) dreams, generating novel associations between recent and remote memories that are then instantiated during non-REM (NREM) sleep. This hypothesis conflicts with our knowledge of the physiology of NREM and then REM sleep stages and their ordered succession. Moreover, associations during sleep might also involve the extraction of hidden patterns rather than de novo associations.

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Altered heart rate variability during sleep in mild cognitive impairment

SLEEP ◽

10.1093/sleep/zsaa232 ◽

2020 ◽

Author(s):

Shawn D X Kong ◽

Camilla M Hoyos ◽

Craig L Phillips ◽

Andrew C McKinnon ◽

Pinghsiu Lin ◽

...

Keyword(s):

Older Adults ◽

Heart Rate ◽

Heart Rate Variability ◽

Cognitive Impairment ◽

Mild Cognitive Impairment ◽

Eye Movement ◽

Rem Sleep ◽

Nrem Sleep ◽

Sleep Stages ◽

Rapid Eye Movement

Abstract Study Objectives Cardiovascular autonomic dysfunction, as measured by short-term diurnal heart rate variability (HRV), has been reported in older adults with mild cognitive impairment (MCI). However, it is unclear whether this impairment also exists during sleep in this group. We, therefore, compared overnight HRV during sleep in older adults with MCI and those with subjective cognitive impairment (SCI). Methods Older adults (n = 210) underwent overnight polysomnography. Eligible participants were characterized as multi-domain MCI or SCI. The multi-domain MCI group was comprised of amnestic and non-amnestic subtypes. Power spectral analysis of HRV was conducted on the overnight electrocardiogram during non-rapid eye movement (NREM), rapid eye movement (REM), N1, N2, N3 sleep stages, and wake periods. High-frequency HRV (HF-HRV) was employed as the primary measure to estimate parasympathetic function. Results The MCI group showed reduced HF-HRV during NREM sleep (p = 0.018), but not during wake or REM sleep (p > 0.05) compared to the SCI group. Participants with aMCI compared to SCI had the most pronounced reduction in HF-HRV across all NREM sleep stages—N1, N2, and N3, but not during wake or REM sleep. The naMCI sub-group did not show any significant differences in HF-HRV during any sleep stage compared to SCI. Conclusions Our study showed that amnestic MCI participants had greater reductions in HF-HRV during NREM sleep, relative to those with SCI, suggesting potential vulnerability to sleep-related parasympathetic dysfunction. HF-HRV, especially during NREM sleep, may be an early biomarker for dementia detection.

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Development of Sleep-Wake Patterns and Non-rapid Eye Movement Sleep Stages during the First Six Months of Life in Normal Infants

PEDIATRICS ◽

10.1542/peds.69.6.793 ◽

1982 ◽

Vol 69 (6) ◽

pp. 793-798

Author(s):

Susan Coons ◽

Christian Guilleminault

Keyword(s):

Eye Movement ◽

Rem Sleep ◽

Early Period ◽

Nrem Sleep ◽

Distribution Patterns ◽

Reciprocal Relationship ◽

Sleep Stages ◽

Rapid Eye Movement ◽

Wake Patterns ◽

Qualitative Changes

Thirty-one normal infants were selected for 24-hour polygraphic monitoring at different ages during the first six months of life. The development of sleep-wake distribution patterns during day and night was observed. Qualitative changes in non-rapid eye movement (NREM) sleep as it becomes differentiated in stages 1, 2, and 3-4 were measured. Sustained periods of wake are present by 6 weeks of age. After 3 months of age, wake is predictably distributed in late afternoon and early evening. REM sleep is disproportionately distributed within sleep in 24 hours, presenting a higher percent of total sleep during the night. At 4.5 and 6 months of age, stages 2 and 3-4 NREM are coincident during the nocturnal hours and 3-4 NREM sleep peaks in the early period of the night. The decreasing proportion of REM sleep, particularly in its daytime distribution, suggests a reciprocal relationship to the development of wakefulness.

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Order matters: sleep spindles contribute to memory consolidation only when followed by rapid-eye-movement sleep

SLEEP ◽

10.1093/sleep/zsac022 ◽

2022 ◽

Author(s):

Mélanie Strauss ◽

Lucie Griffon ◽

Pascal Van Beers ◽

Maxime Elbaz ◽

Jason Bouziotis ◽

...

Keyword(s):

Eye Movement ◽

Memory Consolidation ◽

Learning Task ◽

Sleep Cycle ◽

Sleep Stages ◽

Sleep Spindles ◽

Rapid Eye Movement ◽

Sequential Hypothesis ◽

Falling Asleep ◽

Negative Effect

Abstract Sleep is known to benefit memory consolidation, but little is known about the contribution of sleep stages within the sleep cycle. The sequential hypothesis proposes that memories are first replayed during non-rapid-eye-movement (NREM or N) sleep and then integrated into existing networks during rapid-eye-movement (REM or R) sleep, two successive critical steps for memory consolidation. However, it lacks experimental evidence as N always precedes R sleep in physiological conditions. We tested this sequential hypothesis in patients with central hypersomnolence disorder, including patients with narcolepsy who present the unique, anti-physiological peculiarity of frequently falling asleep in R sleep before entering N sleep. Patients performed a visual perceptual learning task before and after daytime naps stopped after one sleep cycle, starting in N or R sleep and followed by the other stage (i.e. N-R vs. R-N sleep sequence). We compared over-nap changes in performance, reflecting memory consolidation, depending on the sleep sequence during the nap. Thirty-six patients who slept for a total of 67 naps were included in the analysis. Results show that sleep spindles are associated with memory consolidation only when N is followed by R sleep, that is in physiologically ordered N-R naps, thus providing support to the sequential hypothesis in humans. In addition, we found a negative effect of rapid-eye-movements in R sleep on perceptual consolidation, highlighting the complex role of sleep stages in the balance to remember and to forget.

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Hemodynamic changes associated with obstructive sleep apnea followed by arousal in a porcine model

Journal of Applied Physiology ◽

10.1152/jappl.1993.75.4.1439 ◽

1993 ◽

Vol 75 (4) ◽

pp. 1439-1443 ◽

Cited By ~ 36

Author(s):

J. M. Pinto ◽

E. Garpestad ◽

J. W. Weiss ◽

D. M. Bergau ◽

D. A. Kirby

Keyword(s):

Heart Rate ◽

Blood Flow ◽

Eye Movement ◽

Coronary Blood Flow ◽

Rem Sleep ◽

Resistance Index ◽

Nrem Sleep ◽

Sleep Stages ◽

Rapid Eye Movement ◽

Obstructive Sleep

To study the effects of airway obstruction (AWO) and arousal on coronary blood flow, mean arterial pressure (MAP), and heart rate, pigs were chronically instrumented with arterial catheters, Doppler flow probes on the left circumflex coronary artery, and electrodes for determination of sleep stages. A modified tracheostomy tube was placed in the trachea to obstruct the upper airway during sleep sessions. In control studies, during non-rapid-eye-movement (NREM) sleep, MAP was 84 +/- 2 mmHg before AWO and increased by 5 +/- 2 mmHg on arousal. MAP was lower during rapid-eye-movement (REM) sleep (62 +/- 2 mmHg), and the increase on arousal was fourfold greater (22 +/- 2 mmHg). Heart rate was similar in both sleep stages (NREM: 120 +/- 4 beats/min; REM: 124 +/- 5 beats/min) and increased significantly on arousal (NREM: 12 +/- 2 beats/min; REM: 18 +/- 1 beats/min). Coronary blood flow was similar during both stages (NREM: 43 +/- 4 ml/min; REM: 46 +/- 8 ml/min) and increased by 12–15% on arousal. Coronary vascular resistance index increased significantly by 24% on arousal from AWO during REM sleep. All increases and decreases were significant at P < 0.05. Receptor blockade studies were performed to assess alpha-adrenergic receptor involvement.

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POLYSOMNOGRAPHY

JMS SKIMS ◽

10.33883/jms.v18i2.270 ◽

2015 ◽

Vol 18 (2) ◽

pp. 165-166

Author(s):

Juhi Jamwal ◽

Suhail Malik

Keyword(s):

Sleep Disorders ◽

Eye Movement ◽

Rem Sleep ◽

Ph Monitoring ◽

Body Position ◽

Nrem Sleep ◽

Response To Treatment ◽

Sleep Stages ◽

Normal Person ◽

Rapid Eye Movement

Polysomnography (PSG) is the gold standard diagnostic test for several sleep disorders. It records , analyzes, & interprets multiple simultaneous physiologic characteristics during sleep. These parameters include brain waves, the oxygen level in the blood, heart rate and breathing, body position, as well as eye and leg movements, along with synchronized audiovisual monitoring. Moreover, in certain conditions, additional parameters may be included such as esophageal pH monitoring, esophageal manometry , and overnight blood pressure monitoring. The test is usually performed at a sleep disorders unit within a hospital or at a sleep disorders centre. Sleep architecture is largely divided into non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM is further divided into three stages: N1, N2, and N3 : N3 being the deepest stage of sleep. REM sleep alternates with NREM sleep and a normal person usually has 4–6 cycles of REM and NREM sleep . Monitoring of the different sleep stages, sleep interruptions, movements, and the other respiratory and cardiac signals are clinically helpful for identifying the nature of patient’s sleep problems and assessing response to treatment. JMS 2015;18(2):165-166

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Shining a Light on the Mechanisms of Sleep for Memory Consolidation

Current Sleep Medicine Reports ◽

10.1007/s40675-021-00204-3 ◽

2021 ◽

Author(s):

Michelle A. Frazer ◽

Yesenia Cabrera ◽

Rockelle S. Guthrie ◽

Gina R. Poe

Keyword(s):

Rem Sleep ◽

Neural Activity ◽

Memory Consolidation ◽

Strong Support ◽

Nrem Sleep ◽

Future Research ◽

Sleep Spindles ◽

Slow Oscillations ◽

Theta Waves ◽

Learning Tasks

Abstract Purpose of review This paper reviews all optogenetic studies that directly test various sleep states, traits, and circuit-level activity profiles for the consolidation of different learning tasks. Recent findings Inhibiting or exciting neurons involved either in the production of sleep states or in the encoding and consolidation of memories reveals sleep states and traits that are essential for memory. REM sleep, NREM sleep, and the N2 transition to REM (characterized by sleep spindles) are integral to memory consolidation. Neural activity during sharp-wave ripples, slow oscillations, theta waves, and spindles are the mediators of this process. Summary These studies lend strong support to the hypothesis that sleep is essential to the consolidation of memories from the hippocampus and the consolidation of motor learning which does not necessarily involve the hippocampus. Future research can further probe the types of memory dependent on sleep-related traits and on the neurotransmitters and neuromodulators required.

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Manipulating neural activity and sleep-dependent memory consolidation

Neuroforum ◽

10.1515/nf-2020-0002 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Maryam Ghorbani ◽

Lisa Marshall

Keyword(s):

Eye Movement ◽

Neural Activity ◽

Memory Consolidation ◽

Nrem Sleep ◽

Neural Oscillations ◽

Rapid Eye Movement ◽

Hippocampus Dependent Memory

AbstractSleep contributes actively to the consolidation of many forms of memory. This review describes the neural oscillations of non-rapid eye movement (NREM) sleep, the structures underlying these oscillations and their relation to hippocampus-dependent memory consolidation. A main focus lies on the relation between inter- and intraregional interactions and their electrophysiological representation. Methods for modulating neural oscillations with the intent of affecting memory consolidation are presented.

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Sleep Disorders

10.2310/psych.6176 ◽

2015 ◽

Author(s):

Sudhansu Chokroverty

Keyword(s):

Sleep Apnea ◽

Sleep Disorders ◽

Eye Movement ◽

Rem Sleep ◽

Sleep Apnea Syndrome ◽

Nrem Sleep ◽

Rapid Eye Movement ◽

Circadian Rhythm Sleep Disorders ◽

Apnea Syndrome ◽

Sleep Mechanism

Recent research has generated an enormous fund of knowledge about the neurobiology of sleep and wakefulness. Sleeping and waking brain circuits can now be studied by sophisticated neuroimaging techniques that map different areas of the brain during different sleep states and stages. Although the exact biologic functions of sleep are not known, sleep is essential, and sleep deprivation leads to impaired attention and decreased performance. Sleep is also believed to have restorative, conservative, adaptive, thermoregulatory, and consolidative functions. This review discusses the physiology of sleep, including its two independent states, rapid eye movement (REM) and non–rapid eye movement (NREM) sleep, as well as functional neuroanatomy, physiologic changes during sleep, and circadian rhythms. The classification and diagnosis of sleep disorders are discussed generally. The diagnosis and treatment of the following disorders are described: obstructive sleep apnea syndrome, narcolepsy-cataplexy sydrome, idiopathic hypersomnia, restless legs syndrome (RLS) and periodic limb movements in sleep, circadian rhythm sleep disorders, insomnias, nocturnal frontal lobe epilepsy, and parasomnias. Sleep-related movement disorders and the relationship between sleep and psychiatric disorders are also discussed. Tables describe behavioral and physiologic characteristics of states of awareness, the international classification of sleep disorders, common sleep complaints, comorbid insomnia disorders, causes of excessive daytime somnolence, laboratory tests to assess sleep disorders, essential diagnostic criteria for RLS and Willis-Ekbom disease, and drug therapy for insomnia. Figures include polysomnographic recording showing wakefulness in an adult; stage 1, 2, and 3 NREM sleep in an adult; REM sleep in an adult; a patient with sleep apnea syndrome; a patient with Cheyne-Stokes breathing; a patient with RLS; and a patient with dream-enacting behavior; schematic sagittal section of the brainstem of the cat; schematic diagram of the McCarley-Hobson model of REM sleep mechanism; the Lu-Saper “flip-flop” model; the Luppi model to explain REM sleep mechanism; and a wrist actigraph from a man with bipolar disorder. This review contains 14 highly rendered figures, 8 tables, 115 references, and 5 MCQs.

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