How we move is universal: Scaling in the average shape of human activity

DANTE R. CHIALVO; ANA MARIA GONZALEZ TORRADO; EWA GUDOWSKA-NOWAK; JEREMI K. OCHAB; PEDRO MONTOYA; MACIEJ A. NOWAK; ENZO TAGLIAZUCCHI

Papers in Physics

apers in Physics

Año: 2015

1852-4249

Human motor activity is constrained by the rhythmicity of the 24 hours circadian cycle,including the usual 12-15 hours sleep-wake cycle. However, activity fluctuations also appearover a wide range of temporal scales, from days to a few seconds, resulting from theconcatenation of a myriad of individual smaller motor events. Furthermore, individualspresent different propensity to wakefulness and thus to motor activity throughout the circadiancycle. Are activity fluctuations across temporal scales intrinsically different, or isthere a universal description encompassing them? Is this description also universal acrossindividuals, considering the aforementioned variability? Here we establish the presence ofuniversality in motor activity fluctuations based on the empirical study of a month of continuouswristwatch accelerometer recordings. We study the scaling of average fluctuationsacross temporal scales and determine a universal law characterized by critical exponentsα, τ and 1/µ. Results are highly reminiscent of the universality described for the averageshape of avalanches in systems exhibiting crackling noise. Beyond its theoretical relevance,the present results can be important for developing objective markers of healthy as wellas pathological human motor behavior.