Exploring the Importance of Daylight: Insights and review from "Are You Getting Enough Daylight?"

Recently the Volkskrant (Dutch newspaper) featured an article in Dutch which translates as "Are you getting enough daylight? Probably not, and that's a bad thing"

Here's a summary of the article:

• The Problem: While the benefits of exercise and the harms of smoking are well-known, the importance of daylight is often overlooked. However, sufficient daylight reduces stress and gloominess and improves sleep quality. People spend 80 to 90 percent of their time indoors, even on the longest day of the year.
• Biological Clock: Light is crucial for regulating our biological clock, a piece of tissue in the middle of our brain that synchronizes various bodily functions. Without sunlight, our biological clock would run on a 24.2-hour cycle, causing us to be out of sync with the Earth. Sunlight re-calibrates this clock daily through light-sensitive cells in the retina, which also regulate melatonin production.
• Lack of Daylight Indoors: Since the invention of the light bulb, our light exposure has become unbalanced: too much artificial light at night and too little daylight during the day. The amount of light needed varies per individual, and older people generally need more light because their eye lenses become cloudier, making it harder for light to reach the retina and potentially leading to sleep problems. The article mentioned that UV and Infrared is blocked especially in the built environment (e.g. windows block Infrared to reduce heat).
• Measuring Light: Outside, under a blue sky, light can reach 100,000 lux (lumen per square meter), and even on a cloudy day, it's about 10,000 lux. Indoors, however, this drops significantly; for example, a desk a few meters from a window might only receive 1,000 lux.
• Recommendations: While current building codes suggest a daylight factor of 2 to 3 percent, this might not be enough on gloomy days. International experts recommend a minimum m-EDI (Melanopic Equivalent Daylight Illuminance) of 250 lux throughout the day, a level most people don't achieve indoors. The article emphasizes that "the more light the better" during the day, provided it doesn't cause glare or sunburn. LED lighting is a positive development but not fully comparable to daylight. The article advises getting outside, especially in the morning, to help kickstart the day.

Here are some potential shortcomings or areas for more specific advice:

• More Specific Actionable Advice: The article generally recommends getting "more daylight" or going "outside". It would be more helpful to be specific, e.g., "Aim for at least 30 minutes of outdoor exposure at brightest time of the day, especially in the morning or around noon."
• Emphasis on Timing: While it mentions picking up the morning light, it could further emphasize the critical role of bright light exposure in the morning and early afternoon for circadian rhythm regulation, as this is when the biological clock is most sensitive to light for synchronization. People could also opt to walk or cycle to their public transport or workplace. Or park their car 10 mins away, so you are adding an extra walk and daytime exposure.
• Clarifying 250 Lux m-EDI: The article states that 250 lux m-EDI is a recommendation, but most people don't achieve it indoors. People should embrace natural daylight, in fact access to daylight and quality views enhance our wellbeing. In spaces where this is not possible, dedicated Circadian Lighting can help. For example CircadianLux has successfully implemented circadian light that enhances visual appeal and wellbeing by adding better lighting. Another point is that this light can be measured with e.g. a RoomYou1 sensor which monitors m-EDI on a 1,2,5,10 minute interval. Measuring light beyond lux will help understand the potential shortcomings so solutions can be found.
• Nuance on Infrared Blocking: The article mentions that in buildings, ultraviolet and infrared radiation are blocked. While UV blocking is generally beneficial, a deeper dive could discuss that blocking all infrared might not be entirely advantageous, as some research suggests certain wavelengths of infrared light can have positive effects on mitochondrial function and overall health. A holistic view of light includes more than just the visible spectrum and its impact on the eyes. And whilst I would not advocate for UV in general lighting fixtures, we should note that UV helps with vitamin D production. Beyond the eye, the skin also has photo receptors which impact our cellular energy and more. 

Jille Kuipers, innovation manager at LuxBalance adds: In the modern built environment, circadian lighting is essential. Where natural daylight is not available, new solutions help by mimicking the natural rhythm at the right time and in the right amount. Let's also critically examine what we block; not all infrared is bad, and a one-sided focus on energy efficiency falls short. A balanced approach is crucial for our well-being.