Can Extra Daytime Light Exposure Improve Well-Being and Sleep? A Pilot Study of Patients With Glaucoma.

Aki Kawasaki,Mohamad El Wardani,Mirjam Münch,Morgane Udry

doi:10.3389/fneur.2020.584479

Abstract

Glaucoma damages retinal ganglion cells, including intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells modulate various non-visual physiological and psychological functions which are modulated by light. In patients with glaucoma, we assessed the effect of daily bright light exposure (LE) on several melanopsin-dependent functions, such as the pupil constriction, circadian rest-activity cycles, sleep and subjective well-being including relaxation, alertness and mood. Twenty patients participated in the study (9 women, 11 men, mean age = 67.6 ± 7.5 y). Pupillometry was performed before the LE weeks and repeated on the last day of LE. The post-illumination pupil response (PIPR) was calculated as a proxy for melanopsin-dependent activation. Participants continuously wore an activity monitor and self-assessed sleep quality, well-being and visual comfort for 7 days before and during 4 weeks of daily bright LE (30 min to 10,000 lux polychromatic bright white light). After the LE, there was a significantly greater PIPR and higher subjective sleep quality when compared to the pre-LE week (p < 0.05), but no significant changes in 24-h rhythms or sleep parameters. A greater PIPR was correlated with an increase in circadian amplitude and higher inter-daily stability (derived from rest-activity cycles; p < 0.05). In a small group of patients with glaucoma, scheduled daily bright light exposure could improve subjective sleep quality. These findings highlight the importance to evaluate and maintain non-visual functions at different levels in patients with progressive loss of ipRGCs.

Highlights

Glaucoma is a common optic neuropathy that results in retinal ganglion cell loss
In a small group of patients with glaucoma of heterogeneous types and without severe visual loss, we found that increasing their daily light exposure during daytime by adding a tablebased light box in their home had a favorable effect on subjective sleep quality and increased their melanopsin dependent pupil response (PIPR)
There was an increase in post-illumination pupil response (PIPR) at the end of 4 weeks of light exposure and there was a significant correlation between the change in PIPR and the change in 24-h amplitude and inter-daily stability of rest-activity cycles during light exposure

Summary

Introduction

In patients with advanced glaucoma, loss of intrinsically photosensitive retinal ganglion cells (ipRGCs) has been demonstrated [1]. The ipRGCs express melanopsin and synapse centrally to modulate a variety of non-visual physiological functions such as the pupil, circadian rhythms, alertness and sleep [2]. Reduced capacity to entrain to light and was first shown in glaucomatous rats [3, 4] Extending those findings to patients with glaucoma, Light Exposure, Sleep, and Glaucoma even those with mild visual dysfunction may demonstrate abnormal light responses including reduced acute alerting effects to light, reduced light-induced suppression of nocturnal melatonin and reduced pupil light reflex to selected light stimuli as these are effects mediated by melanopsin [5,6,7,8,9,10]. Glaucoma patients have been shown to have a higher prevalence for impaired executive daytime functions, depressive symptoms, impaired mood [11, 12] and anxiety [13] and clinical implications have been discussed [for a reviews see [14,15,16]]

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