Dawn simulation light: A potential cardiac events protector

Antoine U. Viola, Virginie Gabel, Sarah L. Chellappa, Christina Schmidt, Vanja Hommes, Eleonora Tobaldini, Nicola Montano, Christian Cajochen

Research output: Contribution to journalArticle


Objective/Background: Major cardiovascular events frequently increase in the morning due to abrupt changes in the sympatho-vagal cardiac control during the transition from sleep to wakefulness. These neural changes are translated into stepwise increases in cardiac functions, resulting in a potential cardiovascular stress. Here, we explored whether light can "optimize" heart rate and its neural control, by actively promoting a less steep transition from sleep to wakefulness, thus minimizing morning cardiovascular vulnerability. Methods: Seventeen healthy young men were awakened 2-hours before their habitual wake-time. In a counterbalanced within-subject design, we applied a control condition (darkness during sleep and dim light during wakefulness) or dawn-simulation-light (DSL) starting 30-minutes before and ending 30-minutes after scheduled wake-up time. Results: Our data reveal a significantly gradient reduction in heart rate during the transition from sleep to wakefulness, when applying DSL as compared to a control condition. Likewise, cardiac sympatho-vagal control smoothly increased throughout the 30-min sleep episode preceding scheduled wake-up under DSL and remained stable for the first 30-min of wakefulness. Interestingly, these effects were mostly driven by changes in the parasympathetic cardiac control. Conclusions: Our data demonstrate for the first time that a non-invasive strategy, as light exposure surrounding the wake-up process, can significantly reduce the deleterious sleep-to-wake evoked cardiac modulation in healthy young men awakened under conditions of increased sleep pressure. A translational approach of this light exposure, which closely resembles natural lighting conditions in the morning, may therefore act as a potential protector for cardiac vulnerability in the critical morning hours.

Original languageEnglish
Pages (from-to)457-461
Number of pages5
JournalSleep Medicine
Issue number4
Publication statusPublished - Apr 1 2015


  • Cardiac control
  • Circadian functions
  • Heart rate
  • Heart rate variability
  • Light

ASJC Scopus subject areas

  • Medicine(all)

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    Viola, A. U., Gabel, V., Chellappa, S. L., Schmidt, C., Hommes, V., Tobaldini, E., Montano, N., & Cajochen, C. (2015). Dawn simulation light: A potential cardiac events protector. Sleep Medicine, 16(4), 457-461. https://doi.org/10.1016/j.sleep.2014.12.016