The power of light: How blue light impacts mood and self-perception

Light has an undeniable influence on how we feel, and this connection goes beyond just how bright or dim our environment is. In recent years, scientists have discovered that different sorts of light play a significant role in influencing our moods and emotions.

Studies have shown that exposure to natural light can improve mood, while dimmer light during the daytime can contribute to sadness and mood disturbances, such as an increased risk of depression and self-harm.

This effect is noticeable in conditions like Seasonal Affective Disorder, where shorter days with less sunlight lead to worsened symptoms.

In particular, blue light seems to play a key role in improving mood and reducing negative emotions. We are exposed to blue light from both natural and artificial sources. Sunlight, where blue light is abundant, is the primary natural source.

Increasingly, we are also exposed to artificial sources of blue light, including LED screens from smartphones, computers, and TVs, as well as LED and fluorescent lighting in homes and workplaces. Other devices like smartwatches and LED streetlights also contribute.

The science behind light and mood
Light affects mood through a complex, non-visual pathway in our brain, one that works independently of our circadian rhythm, the body's internal clock.

This non-visual effect of light involves specialized cells in the eye called "intrinsically photosensitive retinal ganglion cells". These cells are particularly sensitive to blue light and send signals directly to specific areas of the brain.

This pathway does not rely on the usual visual system but instead connects directly to brain regions that are involved in emotional regulation and decision-making. One of these key areas is the lateral habenula, which is involved in how we process emotions, rewards, and motivation.

Research has shown that when the special eye cells are activated by blue light, the activity in the lateral habenula decreases, which can lead to improvements in mood.

Other areas of the brain, such as the ventromedial prefrontal cortex, also receive input from these cells and are thought to play a role in how light influences emotional responses - and even how we think about ourselves.

Investigating blue light’s Impact on self-perception - the study

A recent study investigated how light influences our perception of ourselves.

The study involved 35 healthy participants who were exposed to either blue-enriched or blue-depleted light while completing a task designed to measure their self-referential thoughts.

The study found that under blue-enriched light, participants were more likely to reject negative words and endorse positive ones when asked if they applied to themselves. This effect was evident even though both types of light had the same brightness.

The researchers used computational models to track how quickly participants made decisions during the task, revealing that blue light facilitated faster rejection of negative self-judgments.

Conversely, under blue-depleted light, participants took longer to make these decisions, suggesting that it was harder for them to reject negative words.

The study's results suggest that blue-enriched light helps individuals more easily reject negative thoughts about themselves, potentially improving self-esteem and mood.

The broader perspective

Modern society is filled with artificial lighting, much of which is rich in blue wavelengths. This constant exposure may be influencing our emotions and thoughts in ways that we are not fully aware of.

On the other hand, by enhancing our ability to reject negative self-descriptions, blue light offers a promising new way to address mood disorders and enhance emotional resilience.

As our understanding of light's impact on the brain grows, it may become a valuable tool for improving mental well-being in today's fast-paced, light-saturated world.

About the scientific paper:

First author: Malisa T. Burge, Australia
Published: Sleep, February 2025
Link to paper: https://academic.oup.com/sleep/advance-article/doi/10.1093/sleep/zsaf034/8039206?searchresult=1