Blue Light Therapy: How Indoor Lighting Impacts Human Health

By PowerHouse Growers | Sustainable Living, Urban Design

Scientific and psychological researchers are beginning to connect the dots between human exposure to indoor lighting and our overall human health. This research is important in providing health recommendations so that our biological condition can be more conducive to better quality of life as a result of our sleep patterns and energy levels.

Before we discuss how indoor lighting impacts human health, we need to first look at what regulates our human activity based on the amount of daylight we receive.

Circadian Rhythms: The Human Biological Clock

The circadian rhythm, often referred to as our biological clock, is the built-in and self-sustaining regulator found in plants, animals, and biological organisms. These circadian rhythms generally operate in 24-hour cycles – one full day. This is how the connection can be drawn between light exposure and sleep patterns. As humans, we instinctively know that when it’s light out we need to be active, and when it’s dark out we need to be resting.

The human health problem within this is often encountered when daylight becomes more limited. This could be either during winter months, or because a significant amount of time is spent indoors. Both of these factors have been known to throw off our circadian rhythms, potentially leading to chronic health conditions.


Understanding the body’s circadian rhythm can help humans maximize their health and performance levels. Image via End This Trend 2014.

Health Impacts from Desynchronized Circadian Rhythms

When circadian rhythms are out-of-sync it may begin, over time to lead to many different types of health conditions. The research is indicating that the following are some of the types of conditions we may be developing due to improper balance of our biological clocks – namely, poor sleep patterns.

  • Poor cardiovascular strength
  • Obesity
  • Diabetes
  • Depression and anxiety
  • Mental illness such as bipolar disorder
  • Cancer and tumoral diseases

The good news is that our circadian rhythms can be trained and regulated just by adjusting our lifestyle. This is important news for those who work shift-work hours and are awake at night when they have no exposure to daylight. It’s also important awareness for anyone who has irregular sleep patterns or is not receiving enough sleep in general. By training our circadian rhythms, we can increase the stability in our hormone levels like serotonin and melatonin.


The amount and consistency of light received throughout the day impacts our body’s circadian rhythm. Image via Keith Hunter Photography.

Indoor Lighting Impacts Human Health

As mentioned, because our circadian rhythms operate on a 24-hour cycle, our exposure to daylight is a crucial element in maintaining consistency in our built-in clock. Being exposed to an adequate amount of daylight during the day is essential in maintaining balance in our circadian rhythms. Largely this will depend on an individual’s lifestyle. Here’s what the sleep studies and psychological research are saying about how light affects humans:

1. Light Timing – Morning & Night

Our circadian rhythm’s positive effects can be enhanced if we are exposed to daylight immediately upon wakening. Alternatively, if we are exposed to daylight or certain types of indoor lighting before rest, our circadian rhythm will be delayed. If your circadian rhythm is advanced you will likely wake up earlier during the following days, while a delay in your circadian rhythm means you will likely feel the need to sleep in during the following days.

2. Amount & Duration of Light Exposure

Both the length and consistency of light exposure affect a human’s biological clock. Longer and more consistent light exposure has more positive effects on our sleep patterns than shorter and intermittent periods of light exposure. This why even indoor lighting impacts our human health, especially if we don’t spend much time outdoors.

3. Light Intensity & Spectrum

For those of us that spend our time in offices, we know that natural daylighting is scarce. Certain kinds of artificial lighting are known to have negative impacts on our mental alertness, which also impacts our circadian rhythm. Daytime exposure to short wavelength lighting (blue colored light) is known to have positive effects on mental alertness and overall cognitive function. However, exposure to blue light at night can damage our sleep patterns.


LED Lighting is a smarter option for how indoor lighting impacts human health. Image via demarcomedia, Shutterstock.

Blue Light Therapy

For those of us working indoors during the day, we tend to opt for coffee to maintain our mental alertness. However, a study compared the effectiveness between blue light exposure and caffeine consumption as it impacted human daytime alertness and cognitive function. In this study that participants were shown to maintain better mental alertness and avoid distractions better when exposed to one hour of blue light as opposed to consuming 240 mg of caffeine.

This raises the concern over our built environment and our exposure to blue light as an alternative to daylighting in an office setting. According to experts, architectural design should be re-examined so as to include indoor lighting that positively affects human health and performance. By creating a built environment that enhances human well-being, we will likely notice a shift in performance, much like the evidence shown in the WorldGBC’s recent report on Healthy Offices.

Putting the solutions into action within our built environment, such as blue light therapy, will help to train our circadian rhythm during the day and maintain our cognitive functions and levels of happiness and well-being. This research is important in establishing a standard for urban design as it’s clear that our choice of indoor lighting impacts our human health.

Feature Image: Blue spectrum lighting is shown to make the brain more alert. Image via DailyMail UK.

About The Author

PowerHouse Growers
PowerHouse Growers teaches you how to sustainably integrate urban agriculture into your cities, businesses, and homes. We provide clear solutions and benefits for better health, increased productivity, and lower environmental impact. By connecting you with experts, we bring awareness to solutions that may not be top of mind.