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. 2012;24(4):339-42.
doi: 10.1515/ijamh.2012.049.

Reading increases ocular illuminance during light treatment

Aamar Sleemi  1 , Mary A Johnson, Kelly J Rohan, Olaoluwa Okusaga, Timileyin Adediran, Hyacinth Uzoma, Chantelle Walsh, Gloria Reeves, Teodor T Postolache
Affiliations

Reading increases ocular illuminance during light treatment

Aamar Sleemi et al. Int J Adolesc Med Health. 2012.

Abstract

Background: Bright-light treatment is a safe and effective treatment for the management of winter seasonal affective disorder (SAD). In a recent study, we found that the relative duration of reading was positively associated with likelihood of remission after six weeks of light treatment.

Methods: Two technicians measured the illuminance of a light box with a light meter directed towards the center of reading material that was placed on a table in front of the light box. The measurement was also performed after reading material was removed. The two measurements were performed in a randomized order. Friedman analysis of variance with Wilcoxon post-hoc tests were used to compare illuminance with vs. without reading.

Results: The presence of the reading material increased illuminance by 470.93 lux (95% CI 300.10-641.75), p<0.0001.

Limitations: This is a technical report done under conditions intended to mimic those of typical ambulatory light treatment as much as possible.

Conclusions: As reading materials reflect light from the light box, reading during light therapy increases ocular illuminance. If confirmed by future studies using continuous recordings in randomized design, instructing SAD patients to read during light therapy may contribute to a more complete response to light treatment. The downside of specific relevance for students, is that reading, in particular, with bright light in the late evening/early night may induce or worsen circadian phase delay, adversely affecting health and functioning.

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Figures

Figure 1
Figure 1
Differences in light intensity with and without reading material during light treatment, when the light meter is directed away from the light box in the direction of the reading material. Mean and standard errors are illustrated. Light intensity with reading material present was 7223 (150) lux and without reading material was 6752 (137) lux. The difference of 471 lux (95% CI 300–642) was statistically significant (p<0.0001).
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