Many people today are affected by sleep disorders, daytime fatigue and mood imbalances, often as a result of the light in their daily environments. Scientific research has demonstrated that melanopic light, a type of light that affects our biological rhythms, has a significant impact that extends beyond our visual perception. In this article, we will explore the nature of melanopic light and its significance in regulating bodily functions.
What is Melanopic Light?
Melanopic Light is a specific band of light (around 460 nm) that stimulates human melanopsin very effectively. The human retina contains a type of "intrinsically photosensitive retinal ganglion cells (ipRGCs)" , which have melanopsin distributed on their surface. More importantly, the main function of ipRGCs is to process the non-visual responses to light. These cells are highly sensitive to melanopic light. Once activated by melanopsin, ipRGCs send signals to the suprachiasmatic nucleus (SCN), the brain's master circadian clock, which controls rhythmic processes and sleep-wake cycles. If people are exposed to light of this specific band, their circadian rhythm phase shift will be significantly changed, which will have a significant impact on their sleep patterns, alertness and emotional state.
Melanopic-EDI & Melanopic-DER
Melanopic equivalent daylight illuminance (Melanopic EDI) is a metric that measures the effect of a light source on the human non-visual system, including circadian rhythms. The word "equivalent" in its name highlights the fact that it shows how much natural daylight is needed to have the same biological impact on the human body as the current lighting environment.
Melanopic Daylight Efficacy Ratio (Melanopic DER) is essentially a spectral index used to evaluate the "biological influence" of artificial light sources. It does not simply measure the brightness or color of light, but focuses specifically on the intensity of the effect of light on the human circadian rhythm system, thus helping to select lighting that promotes health and optimises medical lighting environments to align with natural physiological needs.
Designing lighting environments that are not only aesthetically pleasing but also essentially supportive of our long-term circadian health will be made easier with an understanding of these metrics.
How Melanopic Light Affects Human Health
- Regulating Circadian Rhythms
The body's circadian rhythm, a 24-hour cycle regulating physiological functions like hormone secretion and sleep-wake patterns, relies on synchronization with melanopic light. Adequate exposure to melanopic light, particularly from morning sunlight, signals the brain and body to awaken by inhibiting melatonin production. However, insufficient exposure to natural light in the early morning can disrupt the circadian rhythm, resulting in inadequate suppression of melatonin production and insufficient stimulation of cortisol release. These disruptions can cause difficulty waking up, reduced daytime alertness and potential sleep disorders, further affecting people’s long-term well-being.
- Mental Alertness & Cognition
Research indicates that receiving sufficient melanopic light during daylight hours can significantly enhance our capacity for concentration, alertness, and clear thinking. This is because melanopic light effectively stimulates the ipRGCs, which send strong activating signals to the parts of the brain responsible for attention and executive function. By stabilising cortisol rhythms and reducing sleepiness, exposure to melanopic light during the day helps to optimise cognitive performance, memory formation and mental clarity.
- Achieving Better Sleep
Melanopic light, which is different from regular light, regulates the secretion of melatonin, thereby improving the quality of sleep at night. Exposure to melanopic light in the morning can accelerate the onset of sleep and increase the duration of deep sleep. Specifically, it can improve sleep architecture by increasing deep sleep by 15–20% and reducing night-time awakenings by 25–30%, while also mitigating the effects of seasonal variations on sleep. The insufficient presence of melanopic light in modern indoor environments can disrupt circadian rhythms, making the supplementation of this light beneficial for healthier sleep.
Application Examples for Optimizing Melanopic Light Exposure
Harnessing the power of melanopic light doesn't require complex technology; it's about making small, conscious changes to your daily habits and environment. Here are two practical examples of how to optimize your light exposure for better health and well-being.
- Healthcare Patient Room
Time-based changes to the lighting spectrum and intensity are necessary in a hospital ward to maximize melanopic light exposure and support patients' circadian rhythms.
Morning: for a gentle initiation of the patient’s physiological rhythm, a medium-intensity light source with a red dominance is recommended, as it can effectively mimic the natural glow of sunrise.
Daytime: during daylight hours, switching to cool-toned, high-intensity lighting—with a spectral peak around 480 nm—helps boost melanopic stimulation. This adjustment not only promotes alertness but also supports the synchronization of the patient’s circadian rhythm.
Night: to replicate the sunset spectrum and assist the patient’s body in transitioning toward a restful state, nighttime lighting should be adjusted to a warm, red-hued setting with low intensity. Once the patient falls asleep, ambient light levels must be maintained below 1 lux; this is critical for preserving sleep quality and preventing the suppression of melatonin.
- Office Room
Smart lighting techniques that support our natural rhythms are increasingly being used in modern workspaces to help office workers stay alert and focused throughout the day. During the day, we should use cooler-toned, brighter lights with a unique combination of wavelengths peaking between 450 and 530 nm, as these strongly stimulate the body's melanopic light response. Since people often become less alert in the morning and afternoon, this kind of light is particularly beneficial at these times.
Suggestions for Gaining Benefits of Melanopic Light
Here are practical and effective suggestions to help you gain the benefits of melanopic light in your daily life:
1. Maximize Natural Light Exposure During the Day
- Spend time outdoors
- Work near windows
- Open blinds and curtains
2. Use Appropriate Artificial Lighting:
- Choose lighting solutions that mimic natural daylight
- Consider dynamic lighting solutions
- Supplement with task lamps
3. Minimize Melanopic Light Exposure in the Evening
- Use dim, warm-colored lights
- Reduce blue light from screens
- Avoid bright overhead lights
As we learn more about the profound impact of light on human health, it is clear that adopting melanopic lighting is not just a luxury, but a necessity for creating healthy, productive and human-centric indoor lighting environments. UPSHINE Lighting provides the ideal light that not only helps people see better, but also makes them feel better and function at their best. Should you wish to switch to healthier lighting options, we welcome you to get in touch.
