The National Institute of Mental Health of the Czech Republic, in collaboration with the Third Medical Faculty of Charles University, states that the blue component of the light spectrum improves cognitive function and increases attention (the procognitive effect), but at the same time suppresses the secretion of melatonin for quality sleep if a person is exposed to it in the evening and at night.

The blue spectral component of light enhances cognitive functions, especially attention and the executive function.

Research has shown that the effects of blue light on cognitive performance are particularly pronounced in tasks requiring attention and performance. The mechanisms of these effects are related to the intrinsically photosensitive ganglion cells of the retina, which are particularly sensitive to the blue light spectrum and directly affect the circadian system and cognitive processes. Studies have shown that when exposed to blue light, subjects performed significantly better on subjective and objective EEG measures of attention than with other light modalities. The procognitive effect of blue light was also confirmed by studies examining cognitive activity using P300 evoked potentials (ERPs), where blue light increased the amplitude of the P300, while light with longer wavelengths did not show this effect.

Blue light suppresses the production of the hormone melatonin and thus disrupts the natural functioning of circadian rhythms when exposed to it in the evening and at night

The problem arises if the human body is also exposed to blue light in the evening and at night. Blue light has been found to disrupt circadian rhythms, affect neuroendocrine systems and contribute to the development of diseases of civilization such as obesity, diabetes, depression and cancer. In addition, evening exposure to artificial light suppresses melatonin synthesis and affects the brain’s electrical activity during sleep.