Abstract
BackgroundThe PLR (pupillary light reflex) can be a marker for pathological medical conditions, such as neurodegenerative or mental health disorders and diseases as well as marker for physiological alterations, such as age, sex or iris color. PLR alterations have been described in people after alcohol consumption, as well. However, the effect of sleep deprivation on PLR parameters is still under debate.MethodsThe aim of this study was to investigate the feasibility of PLR measurements in sleep-deprived and alcohol-exposed participants. In addition, we wanted to identify PLR parameters that were altered by sleep deprivation and alcohol exposure.ResultsAltogether n = 50 participants have been included in this study. Differences in the PLR parameters initial diameter (dinit), latency (∆tlat), acceleration (∆ta), contraction velocity (ϑcon), quarter dilatation velocity (ϑ1/4dil), half dilatation time (∆t1/2), and the line integral (L(0.3500)) have been evaluated between baseline, sleep deprivation, as well as alcohol exposure. In a generalized linear mixed models design, we could observe statistically significant associations between the type of exposure and the PLR parameters half dilatation time and half dilatation time after the first light pulse (all p < 0.05). The participants’ latency showed a significant association in dependence of the type of exposure after the second light pulse (p < 0.05).ConclusionOur study delivers first promising results to further develop devices that may identify conditions that impair the ability to work or drive.
Highlights
The pupillary light reflex (PLR) can be a marker for pathological medical conditions, such as neurodegenerative or mental health disorders and diseases as well as marker for physiological alterations, such as age, sex or iris color
In this study, we were able to identify PLR parameters that were affected by both, sleep deprivation as well as alcohol exposure
The latency, defined as the time between the light pulse and the following initial contraction of the pupil and the half dilatation time, described as the dilatation time after the contraction until the pupil dilatated by half of the contraction amplitude, showed a statistically significant association between type of exposure and PLR parameter alterations
Summary
The PLR (pupillary light reflex) can be a marker for pathological medical conditions, such as neurodegenerative or mental health disorders and diseases as well as marker for physiological alterations, such as age, sex or iris color. One major driver for accidents is fatigue, in particular, after long working shifts [1, 2]. The determination of the PUI consists of an 11 min recording of the pupil diameter during which the driver is forced to pause. Besides the PUI, Rozanowski et al determined parameters of the pupillary light reflex (PLR) in order to investigate the level of fatigue [8]. The authors identified parameters of the PLR that were altered by fatigue and concluded, that the measurement of the PLR might be a useful tool to estimate fatigue, but quite faster in comparison to the PUI determination. A further study proved that the area under the curve of the PLR is associated with subjective sleepiness during a 24 h assessment [9]
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