Effect of environmental sound and light intense on neurocgnitive functions in rats

Introduction: The hospital's noise levels are generally higher than the suggested threshold during daytime and nighttime. Intensive care units, where the most complicated patients are treated, are some of the noisy places in hospitals. Noiseness causes oxidative stress and makes it uncomfortable, which results in interruption of sleep. By the way, natural light exposure becomes less, and the day and nighttime light cycle, which is the most prominent determinative factor for circadian rhythm, becomes disrupted in the intensive care unit environment. We are concerned that noisiness and lightning situations in the ICU may have adverse physiologic and psychological effects on the patients and hospital staff because of these reasons. These stressors have a voluminous impact on health, which needs to be clarified. Our study aimed at these two environmental factors' effect on neurocognitive function. Materials and Methods: A total of 28 Sprague Dawley rats were used in the study. They were divided into four groups, with 7 rats in each group. Group I; was determined as the group in which there was constant light in the environment but dim at night, group G; there was constant noise in the environment in the normal light-dark cycle, group GI; there was constant light (dim at night) and noise together in the environment, and group K as control group with normal noise and light-dark cycle. Intensive care light and noise conditions are examined on data at the literature. It has been reported that daylight levels are between 70-200 lux, night light levels are 1,7-20 lux. 24 hour average noise levels are measured approximately 64 decibels (dB). Also average ICU lenght of stay described as 7 days in the literature. For 7 days all groups exposed light and noise conditions as described above. Group I exposed daylight between 07.00 to 23.00 and dimlight for remaining time. Group G exposed to noise continiously. Group GI exposed to noise continiously and daylight between 07.00 to 23.00 and dimlight for remaining time. At the end of the exposure period, memory and memory functions were examined through behavioral experiments. Results: A significant increase in anxiety-like behavior in the elevated plus maze test was detected in the groups exposed to intensive care-like light (group I) or noise (group G) conditions, compared to the control group statistically. Even there were negative noise and light conditions present in the environment (group GI), there was no significant difference in anxiety-like behaviors compared to the control group, but less anxiety-like behavior seen compared to the other two groups. In the open field test, Group GI showed a significant increase in the time spent in the open area and a significant decrease in the time spent in the close area compared to Group G. No significant difference was observed between the groups in the learning and memory tests that evaluated neurocognitive functions. Conclusion: Our study showed that one of the factors, alone either lightness or noise exposure in the general intensive care unit, is relevant to enhanced stress levels in the rats. By the way, we estimate this stress may have a negative impact on neurocognitive functions. Our results suggest that these factors should be more considered during the environmental design of intensive care units.