Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

Wisse P. Van Der Meijden*, Bart H.W. Te Lindert, Jennifer R. Ramauta, Yishul Wei, Joris E. Coppens, Maarten Kamermans, Christian Cajochen, Patrice Bourgin, Eus J.W. Van Someren

*Corresponding author for this work

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Environmental light can exert potent effects on physiology and behaviour, including pupil size, vigilance and sleep. Previous work showed that these non-image forming effects can last long beyond discontinuation of short-wavelength light exposure. The possible functional effects after switching off long-wavelength light, however, have been insufficiently characterized. In a series of controlled experiments in healthy adult volunteers, we evaluated the effects of five minutes of intense red light on physiology and performance during subsequent darkness. As compared to prior darkness, prior red light induced a subsequent sustained pupil dilation. Prior red light also increased subsequent heart rate and heart rate variability when subjects were asked to perform a sustained vigilance task during the dark exposure. While these changes suggest an increase in the mental effort required for the task, it could not prevent a post-red slowing of response speed. The suggestion that exposure to intense red light affects vigilance during subsequent darkness, was confirmed in a controlled polysomnographic study that indeed showed a post-red facilitation of sleep onset. Our findings suggest the possibility of using red light as a nightcap.

Original languageEnglish
Article number20180989
Pages (from-to)1-9
Number of pages9
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1883
Early online date18 Jul 2018
Publication statusPublished - 25 Jul 2018


Data accessibility. The data supporting this article can be found in the electronic supplementary material, which comprises one Excel spreadsheet for each of the three experiments (S1 Data.xlsx, S2 Data.xlsx and S3 Data.xlsx). Authors’ contributions. This study was designed by W.P.v.d.M., C.C., P.B. and E.J.W.V.S. The data were collected by W.P.v.d.M., B.H.W.t.L. and J.R.R., and analysed by W.P.v.d.M., Y.W., J.E.C. and E.J.W.V.S. The results were interpreted by W.P.v.d.M., M.K. and E.J.W.V.S. All authors contributed to the preparation of the manuscript. Competing interests. We declare we have no competing interests. Funding. This project has been funded with support from the NeuroTime Erasmus+: Erasmus Mundus (awarded to C.C., P.B. and E.J.W.V.S.) and the European Research Council (ERC-ADG-2014-671084 INSOMNIA; awarded to E.J.W.V.S.) programs of the European Commission. This publication/communication reflects the views only of the authors, and the Commission cannot be held responsible for any use that may be made of the information contained therein. This work was supported by Project NeuroSIPE 10738 (awarded to E.J.W.V.S.), of the Dutch Technology Foundation STW, which is part of the Netherlands Organization for Scientific Research (NWO) and partly funded by the Ministry of Economic Affairs, Agriculture and Innovation of The Netherlands. Acknowledgements. We thank Brit Giesbertz, Jessica Bruijel, Liz Vink, Jesminne Castricum, Jeske Hendriks and Ruud van der Blom (Netherlands Institute for Neuroscience) for their contribution to the realization of this study.

FundersFunder number
Ministry of Economic Affairs, Agriculture and Innovation of the Netherlands
Netherlands Organization for Scientific Research
Horizon 2020 Framework Programme671084, 737634
European Commission10738
European Research CouncilERC-ADG-2014-671084
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Stichting voor de Technische Wetenschappen


    • Mental effort
    • Post-illumination effects
    • Pupil diameter
    • Sleep propensity
    • Vigilance


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