A study led by University of Manchester neuroscientists revealed that increased daytime light exposure positively impacts various aspects of cognition. The research, published in Communications Psychology and funded by Wellcome Trust, also indicated that stable light exposure across a week and uninterrupted daily exposure had similar positive effects.
Participants in the study demonstrated improved subjective sleepiness, an enhanced ability to maintain focused attention, and reaction speeds that were 7-10% faster under bright light conditions, compared to recent dim conditions. Individuals with earlier bedtimes tended to exhibit greater wakefulness under bright morning light and increased sleepiness under dimmer evening light, in contrast to their peers with later bedtimes.
Dr. Altug Didikoglu, lead author from The University of Manchester, stated that the findings suggest both recent and long-term light exposure positively influences cognitive performance in real-world daily routines. The beneficial outcomes were linked to short-term bright light and consistent light exposure patterns characterized by brighter daytimes, earlier bedtimes, and higher stability in light exposure.
These improvements in cognitive performance hold potential practical implications for health, safety, and work efficiency, especially in environments with low light, during extended work hours, or night shifts. Exposure to bright, stable daytime light was associated with enhanced and sustained attention in a visual search task. Higher daytime light exposure and fewer transitions between light and dark were also correlated with improved cognitive function.
Additionally, higher daytime light exposure and earlier estimated bedtimes showed stronger relationships between recent light exposure and subjective sleepiness. The study determined that the effect of light on cognitive performance was more significant than the effect of the time of day or time awake.
The scientists propose that these effects are likely initiated by the activation of the ipRGC system in the retina. This system contains special photosensitive retinal cells with melanopsin, which are particularly sensitive to blue-green light and are responsible for non-image-forming functions such as regulating circadian rhythms, the pupillary light reflex, and mood.
The study measured the effects of personal ambient light exposure in a sample of 58 adults over seven days of their daily lives. Participants wore a special daylight exposure monitor on their wrists to track light exposure.