Scientists have discovered how daylight improves brain function

Higher levels of daylight have a positive effect on human cognitive abilities, including concentration, wakefulness and reaction speed. This conclusion was reached by neurobiologists from the University of Manchester after studying the effect of light in real everyday life conditions.

The results of the study are published in the journal Communications Psychology.

Unlike previous laboratory experiments, the new study was conducted outside of controlled conditions. Participants continued to live an ordinary life, and scientists analysed how short-term and regular exposure to light affects brain function.

It turned out that in bright daylight people felt less sleepy, better retained attention and responded to tasks 7-10% faster compared to periods of low light. Similar effects were seen with both stable light levels throughout the week and continuous light throughout the day.

In addition, participants who went to bed earlier showed more pronounced alertness under bright morning light and greater drowsiness in the evening under dim light. This suggests a link between light regime, circadian rhythms and cognitive performance.

The study found that stable exposure to bright light during the day and fewer abrupt transitions between light and darkness were associated with more sustained attention. In one task, participants found visual objects faster and more accurately if they were exposed to good light during the day.

Notably, time of day and duration of wakefulness had little effect on the results. The influence of lighting was found to be a more significant factor for cognitive performance than morning or evening hours.

Scientists attribute the effect to the work of special light-sensitive cells in the retina containing the pigment melanopsin. These cells respond primarily to the blue-green spectrum of light and are involved in the regulation of the biological clock, level of wakefulness, mood and pupil response.

The study involved 58 adults who wore special light sensors on their wrist for a week. Additionally, data on cognitive function was collected using the Brightertime mobile app developed at the University of Manchester. Some of the participants also underwent laboratory tests related to pupil response to light.

The authors note that the findings have practical implications. Improving lighting in workplaces, especially in areas with a lack of daylight, long shifts or night work, can improve attention, safety and overall work efficiency.

Artificial light at night has previously been known to disrupt sleep and shift the biological clock. The new study emphasises that sufficient bright light during daylight hours is equally important.