LIGHT, health, mood, and performance

Mammals function on a roughly 24-hour cycle, following what are known as circadian rhythms.

Light is the main driver of the circadian system, controlling bodily processes such as digestion, the release of certain hormones, body temperature and sleep. 

Throughout history, humans have been adapting sleep schedules to rely on the natural day-night cycle, while electric light has only been widely used as a light source for less than 200 years.

The increased use of electric lighting has led to indoor environments relying on electric light rather than daylight. However, reduced exposure to natural light has been linked to the onset of depression and impaired cognitive function in individuals. As well as irregular sleep-wake cycles have been linked to lower academic performance in university students and jobs.

Numerous studies have shown that disruption of the circadian rhythm is linked to obesity, diabetes, depression and metabolic disorders, and exposure to light at night is also associated with negative health effects such as breast cancer and sleep disorders*.

Conversely, exposure to light during the day has been linked to increases in productivity and sleep quality, as well as reduced symptoms of depression in individuals.

The lighting environments where we live and spend our time directly affect our visual, circadian, and mental health. Currently, lighting conditions in most spaces are designed to meet people’s visual needs, but do not consider circadian and mental health. This presents an opportunity for organisations to provide the lighting conditions required to improve health and well-being in their workspaces.

Understanding the specific needs and preferences of users in a space is fundamental to creating effective lighting environments. For example, patients in a hospital ward have different lighting requirements than people in an office environment.

Considering these lighting strategies and the needs of users in any environment can help to improve the overall mood and increase employee productivity.

Precisely in these first days of autumn when it gets dark early, we notice how the energy of the environment naturally descends to internalise, largely due to this lack of light, just look at the trees, the leaves fall off and all the essence is concentrated inside the trunk and roots.

The same thing happens to us, the need to sleep more, to cultivate energy without great excesses, sometimes with changes in mood or appetite, and in some cases, we forget the importance of receiving direct daylight and respecting the circadian cycles as far as possible.

When the lack of natural daylight is sustained, the symptoms of a “Seasonal Affective Disorder /SAD” can lead to an urgent rescue plan: walks in the fresh air, access to daylight, effective artificial light at appropriate times, good conversations, moderate exercise, and an energy nutrition plan to ensure a successful entry into the coming winter.

*Department of Health and Human Services, National Institutes of Health, General Medical Science. New Clues about biological clocks and Health 2014.

María Kindelán
Associate Director
Physical and Emotional