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. 2019 May 10;1(2):240–258. doi: 10.3390/clockssleep1020021

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© 2019 by the authors.

Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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Linear associations between steady-state pupil size and PVT performance and between pupil size variability and subjective fatigue. (A) Regression between steady-state pupil size and mean reaction time during a PVT across all circadian phases. (B) Regression between pupil variability and subjective fatigue (assessed with a VAS) irrespective of circadian phase. (C) Regressions, considering each circadian phase separately, indicating that increase subjective fatigue is associated with decrease pupil size variability. (D) Regressions, considering each circadian phase separately, indicating that increase subjective fatigue is associated with increase pupil size variability. Phases included in panels B and C are indicated in the insets. Refer to main text for outputs of statistical tests. Regressions were used for visual display only, and not as a substitute of the full GLMM statistics presented in Table 2. GLMMs were set according to dependent variables distribution.