0299 TWENTY-FOUR HOUR LIGHT EXPOSURE PATTERN AND SLEEP CONSOLIDATION IN INSOMNIA PATIENTS

Abstract

There is much evidence that links insufficient light exposure to sleep fragmentation. Previous studies reported that the exposure to lower light levels predicted more nighttime awakenings. This study aims to compare light exposure profiles across 24h between insomnia patients and normal controls, and to examine the relationship of light exposure pattern with sleep consolidation. Participants were recruited from three Public Health Centers in a rural area of Korea. The actigraphy recording for 7 days was conducted for each subject. One hundred six insomnia patients (62.27 ± 12.29 years) and 80 normal control (NC) subjects (55.64 ± 13.25 years) were included for our analysis. The raw light data across 24h were log transformed and averaged into hourly bins. The durations of exposure to four different light levels (< 10, 10 to <100, 100 to <1,000, and ≥1,000 lux) and the area under curve (AUC) values of 24h light exposure were obtained. The association of the duration of exposure to each light level with the wake after sleep onset (WASO) severity was examined using multinomial logistic regression analysis. In 24h light exposure profiles, the light intensity during the hour preceding 04h and 07h in the insomnia group was significantly higher than that of the NC group (p<0.05). There was no significant difference in the duration of exposure to each light level and the AUC of 24h light exposure between the insomnia and NC groups. In the combined group, the AUC was negatively correlated with WASO(r=-.22, p <0.01). The duration of exposure to each light level was not significantly associated with the presence of moderate and severe degree of WASO. Insomnia patients were exposed to higher light intensity in early morning hours compared to normal controls, although the light intensity across daytime was not different between the two groups. The sleep consolidation in community-dwelling adults would not be associated with the time spent at a certain light intensity, but with the total amount of 24h light exposure. Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2013R1A1A2009888).