title: Scale-free fluctuations in behavioral performance: delineating changes in spontaneous behavior of humans with induced sleep deficiency.
abstract: The timing and dynamics of many diverse behaviors of mammals, e.g., patterns of animal foraging or human communication in social networks exhibit complex self-similar properties reproducible over multiple time scales. In this paper, we analyze spontaneous locomotor activity of healthy individuals recorded in two different conditions: during a week of regular sleep and a week of chronic partial sleep deprivation. After separating activity from rest with a pre-defined activity threshold, we have detected distinct statistical features of duration times of these two states. The cumulative distributions of activity periods follow a stretched exponential shape, and remain similar for both control and sleep deprived individuals. In contrast, rest periods, which follow power-law statistics over two orders of magnitude, have significantly distinct distributions for these two groups and the difference emerges already after the first night of shortened sleep. We have found steeper distributions for sleep deprived individuals, which indicates fewer long rest periods and more turbulent behavior. This separation of power-law exponents is the main result of our investigations, and might constitute an objective measure demonstrating the severity of sleep deprivation and the effects of sleep disorders.
authors.affiliation: M. Kac Complex Systems Research Center and M. Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland.
authors.forename: Jeremi K
authors.initials: JK
authors.lastname: Ochab
authors.affiliation: M. Kac Complex Systems Research Center and M. Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Tyburczyk
authors.affiliation: Department of Cognitive Neuroscience and Neuroergonomics, Jagiellonian University, Kraków, Poland; Neurobiology Department, Małopolska Center of Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Beldzik
authors.affiliation: CONICET, Buenos Aires, Argentina.
authors.forename: Dante R
authors.initials: DR
authors.lastname: Chialvo
authors.affiliation: Department of Cognitive Neuroscience and Neuroergonomics, Jagiellonian University, Kraków, Poland; Neurobiology Department, Małopolska Center of Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Domagalik
authors.affiliation: Department of Cognitive Neuroscience and Neuroergonomics, Jagiellonian University, Kraków, Poland; Neurobiology Department, Małopolska Center of Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Fafrowicz
authors.affiliation: M. Kac Complex Systems Research Center and M. Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland; Biocomplexity Department, Małopolska Center of Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Gudowska-Nowak
authors.affiliation: Department of Cognitive Neuroscience and Neuroergonomics, Jagiellonian University, Kraków, Poland; Neurobiology Department, Małopolska Center of Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Marek
authors.affiliation: M. Kac Complex Systems Research Center and M. Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland.
authors.forename: Maciej A
authors.initials: MA
authors.lastname: Nowak
authors.affiliation: Department of Cognitive Neuroscience and Neuroergonomics, Jagiellonian University, Kraków, Poland.
authors.forename: Halszka
authors.initials: H
authors.lastname: Oginska
authors.affiliation: M. Kac Complex Systems Research Center and M. Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Szwed
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology; D014851:Wakefulness / Q000502:physiology