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

Sleep cycles are defined as episodes of non-rapid eye movement (non-REM) sleep followed by an episode of REM sleep. Fractal or aperiodic neural activity is a well-established marker of arousal and sleep stages measured using electroencephalography. We introduce a new concept of ‘fractal cycles’ of s...

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Published in:eLife Vol. 13
Main Authors: Rosenblum, Yevgenia, Jafarzadeh Esfahani, Mahdad, Adelhöfer, Nico, Zerr, Paul, Furrer, Melanie, Huber, Reto, Roest, Famke F, Steiger, Axel, Zeising, Marcel, Horváth, Csenge G, Schneider, Bence, Bódizs, Róbert, Dresler, Martin
Format: Journal Article
Language:English
Published: England eLife Sciences Publications Ltd 09.01.2025
eLife Sciences Publications, Ltd
Subjects:
1/f
Adolescent
Adult
Adults
Age
Antidepressants
antidepressants and sleep
aperiodic activity
Brain research
Child
Datasets
Depression - physiopathology
Disease
Electroencephalography
Female
Fractals
Humans
Hypotheses
Male
Mental depression
Middle Aged
Neuroscience
non-REM-REM sleep cycle
Polysomnography
REM sleep
Sleep
Sleep - physiology
sleep cycles
Sleep Stages - physiology
Sleep, REM - physiology
Time series
Young Adult
aperiodic activity
sleep
non-REM-REM sleep cycle
sleep cycles
neuroscience
1/f
antidepressants and sleep
human
ISSN:2050-084X, 2050-084X
Online Access:Get full text
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Summary:Sleep cycles are defined as episodes of non-rapid eye movement (non-REM) sleep followed by an episode of REM sleep. Fractal or aperiodic neural activity is a well-established marker of arousal and sleep stages measured using electroencephalography. We introduce a new concept of ‘fractal cycles’ of sleep, defined as a time interval during which time series of fractal activity descend to their local minimum and ascend to the next local maximum. We assess correlations between fractal and classical (i.e. non-REM – REM) sleep cycle durations and study cycles with skipped REM sleep. The sample comprised 205 healthy adults, 21 children and adolescents and 111 patients with depression. We found that fractal and classical cycle durations (89±34 vs 90±25 min) correlated positively ( r =0.5, p<0.001). Children and adolescents had shorter fractal cycles than young adults (76±34 vs 94±32 min). The fractal cycle algorithm detected cycles with skipped REM sleep in 91–98% of cases. Medicated patients with depression showed longer fractal cycles compared to their unmedicated state (107±51 vs 92±38 min) and age-matched controls (104±49 vs 88±31 min). In conclusion, fractal cycles are an objective, quantifiable, continuous and biologically plausible way to display sleep neural activity and its cycles.
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ISSN:2050-084X
2050-084X
DOI:10.7554/eLife.96784