Fractal cycles of sleep, a new aperiodic activity-based definition of sleep cycles

eLife, Journal Year: 2025, Volume and Issue: 13

Published: Jan. 9, 2025

Sleep cycles are defined as episodes of non-rapid eye movement (non-REM) sleep followed by an episode REM sleep. Fractal or aperiodic neural activity is a well-established marker arousal and stages measured using electroencephalography. We introduce new concept ‘fractal cycles’ sleep, time interval during which series fractal descend to their local minimum ascend the next maximum. assess correlations between classical (i.e. non-REM – REM) cycle durations study with skipped The sample comprised 205 healthy adults, 21 children adolescents 111 patients depression. found that (89±34 vs 90±25 min) correlated positively ( r =0.5, p<0.001). Children had shorter than young adults (76±34 94±32 min). algorithm detected in 91–98% cases. Medicated depression showed longer compared unmedicated state (107±51 92±38 age-matched controls (104±49 88±31 In conclusion, objective, quantifiable, continuous biologically plausible way display its cycles.

Language: Английский

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Electrophysiological signatures underlying variability in human memory consolidation

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: March 12, 2025

We experience countless pieces of new information each day, but remembering them later depends on firmly instilling memory storage in the brain. Numerous studies have implicated non-rapid eye movement (NREM) sleep consolidating memories via interactions between hippocampus and cortex. However, temporal dynamics this hippocampal-cortical communication concomitant neural oscillations during reactivations remains unclear. To address issue, present study used procedure targeted reactivation (TMR) following learning object-location associations to selectively reactivate human NREM sleep. Cortical pattern coupling were measured with intracranial EEG recordings patients epilepsy. found that TMR produced variable amounts enhancement across a set associations. Successful increased hippocampal ripples cortical spindles, apparent two discrete sweeps reactivation. The first sweep was accompanied by ripple events coupled local activity (cortical high-frequency broadband activity). In contrast, decreased second sweep, while spindle indicated continued processing achieve long-term storage. Taken together, our findings show how dynamic patterns item-level support Here, authors demonstrate enhances consolidation through repeated reactivations, characterized ripples, interactions.

Language: Английский

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Effect of sleep deprivation on fractal and oscillatory spectral measures of the sleep EEG: a window on basic regulatory processes

NeuroImage, Journal Year: 2025, Volume and Issue: 314, P. 121260 - 121260

Published: May 9, 2025

Sleep is vital for sustaining life; therefore, reliable measurement of its regulatory processes significant importance in research and medicine. Here we examine the effect extended wakefulness on putative indicators fundamental sleep (spectral slope spindle frequency) proposed by Fractal Oscillatory Adjustment model regulation involving a healthy young adult sample 35-hour long deprivation protocol. Wearable headband EEG-derived results revealed that NREM electroencephalogram (EEG) spectral estimated 2-48 Hz range an accurate indicator predicted changes depth induced (steepened slopes recovery sleep) or overnight dissipation pressure (flattening during successive cycles). While baseline dynamics center frequency oscillations followed U-shaped curve, timing minimum (the presumed phase indicator) correlated with questionnaire-based chronotype metrics as predicted, different picture emerged sleep. Advanced advanced minima oscillatory frequency, reduced considerably relationship chronotype, but retained partially evolution. Overall, our study supports use EEG homeostatic marker wake-sleep regulation, addition, encourages further measure circadian rhythm, primarily focusing interaction process.

Language: Английский

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Aperiodic neural activity distinguishes between phasic and tonic REM sleep

Journal of Sleep Research, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 26, 2024

Summary Traditionally categorized as a uniform sleep phase, rapid eye movement exhibits substantial heterogeneity with its phasic and tonic constituents showing marked differences regarding many characteristics. Here, we investigate how states differ respect to aperiodic neural activity, marker of arousal sleep. Rapid was assessed using either binary phasic‐tonic ( n = 97) or continuous (in 60/97 participants) approach. Slopes the power component were measured in low (2–30 Hz, high (30–48 60/97) frequency bands Irregularly Resampled Auto‐Spectral Analysis applied on electroencephalography. amplitudes quantified YASA electrooculography 60/97). The approach revealed that state is characterized by steeper low‐band slopes small effect sizes some topographical over datasets. High‐band flatter versus medium‐to‐large all areas both confirmed these findings. temporal analysis within episodes activity preceding following EM events did not cross‐correlate amplitudes. This study demonstrates can serve reliable able differentiate between reflect event intensity. However, could be predicted vice versa, at least scalp

Language: Английский

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Sleep homeostasis occurs in a naturalistic setting

Sleep Health, Journal Year: 2025, Volume and Issue: unknown

Published: March 1, 2025

Language: Английский

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Threshold Values of Sleep Spindles Features in Healthy Adults Using Scalp‐EEG and Associations With Sleep Parameters

Annals of Clinical and Translational Neurology, Journal Year: 2025, Volume and Issue: unknown

Published: April 21, 2025

ABSTRACT Objective Sleep spindles are an electrophysiological fingerprint of the sleeping human brain. They can be described in terms duration, frequency, amplitude, and density, vary widely according to age sex. Spindles play a role sleep wake functions altered several neurological psychiatric disorders. This study established first threshold values for healthy adults using scalp‐EEG explored their associations with other parameters. Methods observational prospective was conducted 80 participants stratified by sex (40.9 years, range 19–74, 50% females). All underwent in‐laboratory polysomnography. during N2 were analyzed automated procedure categorized as fast (> 13 Hz) or slow (≤ Hz). Results For spindles, duration (0.80–1.11 s), frequency (13.4–14.3 Hz), amplitude (5.2–15.2 μV), density (1.0–5.8 spindles/min). (0.79–1.17 (12.3–12.9 (4.1–13.2 (0.03–3.15 From 40 onwards, both types decreased; amplitudes higher females. Higher associated increased excessive daytime sleepiness proportion slow‐wave sleep. Interpretation provides spindle characteristics adults. The findings emphasize importance investigating develop innovative biomarkers disorders gain deeper insights into functioning

Language: Английский

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Fractal cycles of sleep: a new aperiodic activity-based definition of sleep cycles

eLife, Journal Year: 2024, Volume and Issue: 13

Published: May 21, 2024

Sleep cycles are defined as episodes of non-rapid eye movement (non-REM) sleep followed by an episode REM sleep. Fractal or aperiodic neural activity is a well-established marker arousal and stages measured using electroencephalography. We introduce new concept ‘fractal cycles’ sleep, time interval during which series fractal descend to their local minimum ascend the next maximum. assess correlations between classical (i.e. non-REM – REM) cycle durations study with skipped The sample comprised 205 healthy adults, 21 children adolescents 111 patients depression. found that (89±34 vs 90±25 min) correlated positively ( r =0.5, p<0.001). Children had shorter than young adults (76±34 94±32 min). algorithm detected in 91–98% cases. Medicated depression showed longer compared unmedicated state (107±51 92±38 age-matched controls (104±49 88±31 In conclusion, objective, quantifiable, continuous biologically plausible way display its cycles.

Language: Английский

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Sleep homeostasis in a naturalistic setting

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: July 4, 2024

Abstract Sleep, especially NREM sleep depth is homeostatically regulated, as pressure builds up during wakefulness and diminishes deep sleep. Previous evidence from this phenomenon, however, mainly stems experimental studies which may not generalize to an ecologically valid setting. In the current study, we used a dataset of 246 individuals sleeping for at least seven nights each with mobile EEG headband according their ordinary daily schedule investigate effect time spent in on characteristics. Increased prior was associated decreased onset latency, increased efficiency, larger percentage N3 sleep, higher delta activity. Moreover, resulted increase both slope intercept spectrum. As predicted, PSD effects were most prominent earliest hours Our results demonstrate that findings showing after extended settings, awake important determinant characteristics subsequent night. are efficacy restriction, behavioral technique already widely clinical simple but powerful method improve objective quality those problems.

Language: Английский

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Effect of sleep deprivation on fractal and oscillatory spectral measures of the sleep EEG: a window on basic regulatory processes

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Aug. 30, 2024

Sleep is vital for sustaining life; therefore, reliable measurement of its regulatory processes significant importance in research and medicine. Here we examine the effect extended wakefulness on putative indicators fundamental sleep (spectral slope spindle frequency) proposed by Fractal Oscillatory Adjustment model regulation involving a healthy young adult sample 35-hour long deprivation protocol. Wearable headband EEG-derived results revealed that NREM electroencephalogram (EEG) spectral estimated 2–48 Hz range an accurate indicator predicted changes depth induced (steepened slopes recovery sleep) or overnight dissipation pressure (flattening during successive cycles). While baseline dynamics center frequency oscillations followed U-shaped curve, timing minimum (the presumed phase indicator) correlated with questionnaire-based chronotype metrics as predicted, different picture emerged sleep. Advanced advanced minima oscillatory frequency, reduced considerably relationship chronotype, but retained partially evolution. Overall, our study supports use EEG homeostatic marker wake-sleep regulation, addition, encourages further measure circadian rhythm, primarily focusing interaction process.

Language: Английский

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Fractal cycles of sleep: a new aperiodic activity-based definition of sleep cycles

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: July 4, 2023

Abstract Nocturnal human sleep consists of 4 – 6 ninety-minute cycles defined as episodes non-rapid eye movement (non-REM) followed by an episode REM sleep. While are considered fundamental components sleep, their functional significance largely remains unclear. One the reasons for a lack research progress in this field is absence data-driven definition cycles. Here, we proposed to base such on fractal (aperiodic) neural activity, well-established marker arousal and stages. We explored temporal dynamics activity during nocturnal using electroencephalography. Based observed pattern fluctuations, introduced new concept activity-based or “fractal cycles” short, time interval which descends from its local maximum minimum then leads back next maximum. Next, assessed correlations between classical (i.e., non-REM REM) cycle durations. also studied with skipped i.e., where phase expected appear except that it does not, being replaced lightening Regarding sample, examined healthy adults (age range: 18 75 years, n = 205) well children adolescents (range: 8 17 21), group characterized deeper higher frequency Further, major depressive disorder (n 111), condition altered (in addition clinical symptoms). found durations (89 ± 34 min vs 90 25 min) correlated positively (r 0.5, p < 0.001). Cycle-to-cycle overnight showed inverted U-shape both gradual decrease absolute amplitudes descents ascents early late In adults, duration participant’s age negatively −0.2, 0.006). Children had shorter compared young (76 94 32 min, The algorithm detected 91 98% cases. Medicated patients depression longer own unmedicated state (107 51 92 38 0.001) age-matched controls (104 49 88 31 conclusion, objective, quantifiable, continuous biologically plausible way display They useful adult pediatric populations disorder. Fractal should be extensively advance theoretical structure. Highlights - short based cyclic changes Durations correlate, show when seen effective detecting Older shower but not adults. disorder, antidepressant medication associated

Language: Английский

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