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. 2021 Apr 14;11:8161. doi: 10.1038/s41598-021-87596-y

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© The Author(s) 2021

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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Illustrative examples of power spectral density of RR variability during DAY (left panels) and during NIGHT (right panels) computed in one subject of the W_KID group (top panels) and in one subject of W_NOKID group (bottom panels). Each 3D graph shows the power spectral density (PSD, z-axis) of the RR series as a function of the progressive frame of analysis (window, y-axis) and frequency (x-axis).