Light effects in diurnal and nocturnal species: A complex role of the spectral composition.

<p>Light is known to promote sleep in nocturnal species and alertness in day-active animals. Our hypothesis is that the opposite responses to natural polychromatic light may result from higher sensitivity of nocturnal species to green light, and diurnals to blue wavelengths, resulting in hypnogenic and alerting effects, respectively. This can be modeled as different blue and green weights on a balance, explaining either an alerting (higher sensitivity to blue) or sleep-promoting effect (greater sensitivity to green) of white light in diurnal and nocturnal species, respectively.</p

Summary of light parameters influencing sleep and alertness in humans.

<p>In humans, light exerts strong alerting effects that depend upon several parameters, such as dose (irradiance), duration, and the time of day of light exposure. This photic regulation of alertness also critically depends on the spectral composition of light, with blue light as a powerful alerting stimulus, contrary to green light, which might be less powerful to awaken a subject from sleep.</p

A comparison of four methods to estimate dim light melatonin onset: a repeatability and agreement study

Dim light melatonin onset (DLMO) is considered the most reliable circadian phase marker in humans. However, the methods to calculate it are diverse, which limits the comparability between studies. Given the key role of DLMO to diagnose circadian rhythm sleep-wake disorders and determine the optimal timing of chronotherapies, the establishment of clear and validated guidelines on the methodology to assess DLMO is very important. We performed a repeatability study (n = 31) and an agreement study (n = 62) in healthy young adults with hourly blood samples collected under dim light conditions (<8 lux) during a chronobiological protocol. We assessed the repeatability of DLMO with three different methods (fixed threshold, dynamic threshold and hockey stick) across two nights and assessed agreement of each method with the mean visual estimation made by four chronobiologists. Analyses included Bland-Altman diagrams, intraclass correlation coefficients and equivalence tests. The repeatability of the four methods across two nights ranged from good to perfect. The agreement study highlighted that the hockey stick showed equivalent or superior performance (ICC: 0.95, mean difference with visual estimation: 5 min) in healthy subjects compared to the dynamic and fixed thresholds. Thanks to its objective nature, the hockey stick method may provide better estimates than the mean of the visual estimations of several raters. These findings suggest that the hockey stick method provides the most reliable estimate of DLMO within the tested methods and should be considered for use in future studies.</p

S3 Data from Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

Excel spreadsheet containing, in separate sheets, data for statistical analysis and visualization of post-illumination changes in sleep propensity, and sex and age characteristics of the participants in Experiment 3

S4 Supplementary material from Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

PDF document containing the illumination characteristics and details of the statistical analysis in Experiment 1, 2, and 3

S4 Supplementary material from Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

PDF document containing the illumination characteristics and details of the statistical analysis in Experiment 1, 2, and 3

S1 Data from Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

Excel spreadsheet containing, in separate sheets, data for statistical analysis and visualization of post-illumination changes in pupil diameter and response speed, data underlying the pupil diameter trace during the red and blue light exposure paradigm, and sex and age characteristics of the participants in Experiment 1

S1 Data from Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

Excel spreadsheet containing, in separate sheets, data for statistical analysis and visualization of post-illumination changes in pupil diameter and response speed, data underlying the pupil diameter trace during the red and blue light exposure paradigm, and sex and age characteristics of the participants in Experiment 1

S2 Data from Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

Excel spreadsheet containing, in separate sheets, data for statistical analysis and visualization of post-illumination changes in pupil diameter, response speed, R-R interval, ln SDNN, ln RMSSD, and ln SDNN/RMSSD, and sex and age characteristics of the participants in Experiment 2

Sample collections.

*<p>Numbers of samples by country of origin are listed in the <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003270#s3" target="_blank">Methods</a> section.</p><p>Case cohort names represent location of genotyping, and do not reflect country of origin of samples.</p