A real world study led by University of Manchester neuroscientists has shown that higher daytime light exposure positively influences different aspects of cognition.
The first study of its kind, published in the journal Communications Psychology and funded by Wellcome Trust, also showed that stable light exposure across a week and uninterrupted exposure during a day had similar effects.
Participants in the study experienced improved subjective sleepiness, the ability to maintain focused attention and 7-10% faster reaction speeds under bright light when compared to recent dim conditions.
Compared with their peers who went to bed later, participants with earlier bedtimes tended to be both more reliably wakeful under bright morning light – and sleepy under dimmer evening -light.
Lead author Dr Altug Didikoglu from The University of Manchester said: “Our findings show that outside controlled laboratory conditions, where participants continue their daily routines, both recent and long-term light exposure positively influences cognitive performance.
“The beneficial effects were associated with short-term bright light and habitual light exposure patterns characterized by brighter daytimes, earlier bedtimes, and higher consistency in light exposure.”
“These improvements in cognitive performance may have practical implications for health, safety, and work efficiency, particularly in low-light workplaces, during extended work hours, or night shifts.”
Being exposed to bright, stable daytime light was linked to enhanced and more sustained attention in a visual search task in which participant were asked to find a specific target on a page.
Higher daytime light exposure and less switches between light and dark were linked to improved cognitive.
And higher daytime light exposure and earlier estimated bedtimes were also associated with stronger relationships between recent light exposure and subjective sleepiness.
However, neither the time of day nor time awake significantly impacted cognitive performance; the effect of light was stronger than the effect of time of day.
The effects, argue the scientists, are likely initiated by activation of the ipRGC system in the thin layer of light-sensitive tissue at the back of the eye that converts light into signals we interpret as vision, known as the retina.
Special photosensitive retinal cells in the ipRGC system containing the photopigment melanopsin 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 effects of personal ambient light exposure were measured in a sample of 58 adults over seven days of daily life.
The participants wore a special daylight exposure monitor on their wrists which effectively told the scientists how well light exposure influenced their internal body clock.
“The University of Manchester is a public research university in Manchester, England. The main campus is south of Manchester City Centre on Oxford Road.”
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