Using Light To Improve Health
Circadian rhythms are our biological clocks. They influence our sleep and wake times, and they also affect how we feel and function throughout the day. We’ve all experienced jet lag: When we travel across time zones, our circadian rhythms are out of sync with natural light cycles.
Circadian rhythms have been recognized since the early 1800s. In humans, they are controlled by an internal “master clock” called the Suprachiasmatic Nucleus (SCN) that is located in the brain’s hypothalamus. The SCN receives light cues from the environment in order to regulate sleep/wake cycles, body temperature, hormone production and other biological processes.
The effects of circadian rhythms are particularly important in the built environment, because the modern office building is a 24-hour space that’s designed to accommodate people at different times of day. In addition to providing adequate access to natural light, circadian-friendly design means addressing lighting levels, color schemes and other elements in ways that create a positive experience for building occupants.
Circadian rhythms influence human performance. For example, research indicates that people who work during the night shift have a higher risk of developing breast cancer.
The purpose of circadian lighting is to help you be active during the day – attentive, alert and productive – and to help you rest well at night. For example, you might want brighter lights for a general office environment in the daytime and lower lights in an evening study session. In this scenario, regardless of what time it is, the lights should be set to achieve the desired effect regardless of when people are using it. This is where “circadian lighting” comes into play.
Circadian Lighting Design
Circadian lighting design and the global WELL building standard both focus on the importance of circadian rhythms in general well-being and health. According to the National Institute of Health, exposure to artificial light not only increases the risk of certain cancers but has also been linked to depression, diabetes, heart disease, and obesity.
The Circadian Lighting Design Standard (CLDS) is a set of principles for designing interior spaces that account for the natural light emitted by the sun throughout the day. The CLDS recommends that no more than 5% of a space’s total light exposure should be from artificial sources at any given time.
The WELL building standard is a holistic approach to designing and building healthy human habitats. Rather than focusing on one specific element or attribute, WELL assesses an overall wellness score to evaluate spaces based on nine categories:
For each category, there are specific performance metrics such as air quality (VOC levels), daylight access (percentage), or daylight visibility (color rendering index). These metrics are then scored against the WELL “wellness standard” for that category in order to quantify health benefits or risks associated with a given environment.
Going even further than just designing a work environment that balances natural light with the artificial kind – with new LED technology we can now have our lights adapt to the time of day, the setting, or even the number of people in the office. This involves “harvesting” daylight when it’s available, and altering the colour temperature throughout the day ensuring office staff’s circadian rhythms are “reset” so they get a proper sleep.
It’s no surprise that huge companies like Google have made statements about how they’re redesigning their offices to be more bright and airy, with better light-colored walls, managed color temperature, brightness and luminescence of artificial light – with much less emphasis on fluorescent lighting.