Science on Light and Sleep: What It Means for Your Norwegian Winter
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New Science on Light and Sleep: What It Means for Your Norwegian Winter
Understanding the groundbreaking research on circadian-friendly lighting
If you've been following my blog, you know how passionate I am about helping people in Norway navigate our challenging light environment. Recently, a landmark scientific paper was published that changes everything we thought we knew about indoor lighting. This isn't just another study – it's an international expert consensus that provides the first clear, measurable guidelines for healthy light exposure throughout the day and night.
The paper, published in PLOS Biology by Brown and colleagues, brings together leading scientists from around the world to answer a question that affects all of us: How much light do we actually need during the day, and how little should we have at night?
🔬 What Makes This Study Different?
For years, we've designed our indoor lighting based primarily on what helps us see well and is most energy efficient. Seemingly regardless of the health impact on the human body. We have known how light can effect the body for many many years. Even ancient cultures used the power of light to effect health. More recently though, the power of big money, energy efficiency and the "green agenda" have meant that human biology has taken to a back seat in the quest for energy efficiency.
This study focuses on something shifts the focus away from just energy efficiency to something equally important: how light affects our circadian rhythm, sleep quality, alertness, and overall health. The researchers use a new measurement called melanopic equivalent daylight illuminance (melanopic EDI), which measures how light affects the special cells in our eyes that regulate our internal clock.
💡 Think of these cells as your body's light sensors. They don't care much about helping you read a book or see your computer screen – that's the job of your regular vision cells. Instead, these melanopsin-containing cells are constantly asking: "Is it day or night? Should I be alert or sleepy?"
✨ The Three Golden Rules of Healthy Light Exposure
The expert panel provided three simple but powerful recommendations:
☀️ 1. Daytime: Get At Least 250 Melanopic EDI Lux
During the day, especially in the morning and throughout your working hours, you need bright light that has a fair amount of shorter wavelengths (the blue-ish part of the spectrum). The recommendation is a minimum of 250 melanopic EDI lux at eye level.
Why this matters in Norway: Even in midwinter, when our days are short and the sun barely rises above the horizon, outdoor daylight still provides far more of this beneficial light than typical indoor lighting. A cloudy winter day in Oslo can provide 1,000-10,000 melanopic EDI lux, while most office lighting provides less than 200.
This is why I always emphasize: Get outside during daylight hours, even in winter. In Drammen we have a "sunny side" and a "dark side". If you exist on the dark side, the outdoor time becomes even more important. That 30-minute walk during lunch isn't just nice – it's giving your body the light signal it desperately needs to stay alert, regulate your mood, and prepare for good sleep later by creating a big contrast.
If you can't get outside enough (and let's be honest, many of us can't during a Norwegian winter), you need to think carefully about your indoor lighting. Standard warm LED bulbs (2700-3000K) with a typical melanopic ratio of 0.6 or less simply can't provide enough of the right kind of light, even at high illuminance levels.
🌅 2. Evening: Drop to Maximum 10 Melanopic EDI Lux
This is where most of us get it completely wrong. The research shows that starting at least 3 hours before bedtime, you should reduce your light exposure to no more than 10 melanopic EDI lux.
To put this in perspective: A typical living room with standard LED lighting often provides 100-300 melanopic EDI lux. Your smartphone or tablet screen can easily provide 60+ melanopic EDI lux right before bed. Your laptop? Even more. Do you see the problem with having your phone with your in the bedroom? I hope so!
This is why so many Norwegians struggle with sleep. We're not getting enough bright light during our short winter days, and then we're getting far too much of the wrong kind of light in the evening when we should be winding down.
🌙 3. Nighttime: As Dark as Possible (Maximum 1 Melanopic EDI Lux)
Your sleep environment should be as close to darkness as possible – ideally below 1 melanopic EDI lux. If you need some light for safety (getting to the bathroom, for example), it should still stay below 10 melanopic EDI lux.
🏠 What This Means for Your Home
This is where the science meets practical reality. You can't just turn off all your lights at 6 PM in winter – you need to see, you need to cook dinner, help kids with homework, read, relax. So what's the solution?
The key is spectral composition – choosing light sources that provide enough illumination for vision but don't contain the shorter wavelengths that disrupt your circadian rhythm.
⚠️ The Problem with Standard LEDs
Most modern LED bulbs, even "warm white" ones, contain significant amounts of blue and green light. This is great for color rendering and making your home look bright and clean, but terrible for your evening biology. The researchers found that typical 3000-4000K fluorescent or LED lighting has a melanopic daylight efficacy ratio (DER) of 0.6-0.8, meaning you're getting substantial circadian disruption along with your illumination.
✅ The Solution: Circadian-Friendly Evening Lighting
This is why I've carefully curated my circadian and sleep healthy lighting collection. These aren't just "warm" lights – they're specifically designed to provide adequate illumination for evening activities while minimizing the wavelengths that tell your brain "it's daytime, stay alert!"
Incandescent bulbs remain one of the best options for evening lighting. Their warm glow is naturally depleted in short wavelengths, with a melanopic DER well below 0.35. This means you can maintain comfortable illumination levels (around 30 lux in most living spaces) while staying at or below the 10 melanopic EDI lux threshold.
Specially designed low-blue LEDs can achieve similar effects with better energy efficiency. The key is looking for bulbs that aren't just "warm white" but specifically engineered to reduce short-wavelength output.
📊 Real-World Evidence: Does This Actually Work?
The beautiful thing about this paper is that it doesn't just present laboratory data – it reviews dozens of real-world studies showing the benefits of implementing these guidelines:
- Office workers exposed to higher melanopic light during the day (170-290 lux) showed improved sleep quality, better mood, enhanced alertness, and better cognitive performance compared to those in typical offices (under 150 melanopic EDI lux).
- Students in classrooms with higher melanopic lighting showed improved concentration and reading comprehension. The right type of lighting as demonstrated by John Ott over 40 years ago also showed that the right light improved attention and behavior in class. It isn't just light intensity, it is light type!
- Care home residents experienced reduced depression, anxiety, and agitation, along with improved daytime activity when their lighting was optimized.
- Evening light reduction studies consistently show that minimizing blue-enriched light exposure before bed improves melatonin levels, reduces the time it takes to fall asleep, and enhances overall sleep quality.
🎯 Practical Steps You Can Take Today
🌄 Morning and Daytime:
- Get outside as early as possible and for as long as possible – aim for at least 30 minutes of outdoor exposure, even on cloudy days. On clear days this can be as little 5-10 to minutes so don't think if you can't get out for 30 minutes then it isn't worth going out at all.
- Work near windows when possible. In summer open them, in winter just being by them will give you a different ratio of light compared to artificial lighting alone.
- Consider a bright light therapy box (10,000 lux) for morning use, especially during the darkest winter months
- Maximize indoor lighting during working hours but be careful on the type of lighting - look at lighting with the blue artificial peak reduced but with high lumens like this - https://lighttherapy.no/products/daylight-flow-and-daylight-balance-e27-bulbs?variant=42597540692073
🌆 Evening (Starting 3 Hours Before Bed):
- Dim your lights significantly
- Switch to circadian-friendly bulbs – like those in my collection
- Use screen filters or enable "night mode" on devices (though this only reduces blue light by about 50%, so it's not a complete solution)
- Consider red light therapy devices for evening relaxation – they provide illumination without disrupting melatonin
🌃 Nighttime:
- Use blackout curtains or blinds
- Cover or remove LED indicator lights from devices
- If you need lighting for safety, use motion-sensor red lights that won't disrupt your sleep
🇳🇴 Why Winter in Norway Makes This Even More Critical
Living in Norway, we face a unique challenge. During winter, we're often going to work in darkness and coming home in darkness. If our indoor lighting during the day is inadequate (which it usually is), and our evening lighting is too bright and blue-enriched (which it usually is), we're essentially telling our bodies it's evening or nighttime all day long, followed by "daytime" signals when we're trying to sleep.
Is it any wonder that seasonal affective disorder, sleep problems, and winter fatigue are so common here?
The good news is that even modest changes can make a significant difference. You don't need to completely overhaul your life – start with one or two changes:
- Make getting outside during lunch a non-negotiable priority
- Replace the bulbs in your bedroom and living room with circadian-friendly options
- Stop using screens an hour before bed, or at least dim them significantly
🌍 The Bigger Picture
This research represents a fundamental shift in how we think about lighting. For over a century, we've optimized artificial light for vision alone. Now we understand that light is a powerful biological signal that affects virtually every system in our body – from our sleep and mood to our metabolism and immune function.
The standard that these recommendations are based on (CIE S 026:2018) provides, for the first time, a scientifically validated, internationally accepted way to measure and specify lighting for circadian health. This means that in the coming years, we can expect to see lighting products, building standards, and workplace guidelines that take these principles into account.
But you don't have to wait for that future. The science is clear now, the recommendations are straightforward, and the solutions are available today.
💭 Conclusion
As someone who lives in Norway and deeply understands our unique light challenges, I can't overstate how important this research is. The winter darkness isn't going away, but we can work with our biology instead of against it.
Bright light during the day – preferably from getting outside, but supplemented with quality light therapy when needed. Warm, dim, circadian-friendly lighting in the evening. And darkness at night.
It sounds simple because it is simple. But simple doesn't mean easy, especially when our modern world is designed to give us exactly the opposite of what our biology needs.
If you're struggling with winter blues, poor sleep, or just feeling "off" during the dark months, I encourage you to take this science seriously. Your body is crying out for the right light at the right time. Give it what it needs, and you might be surprised by how much better you feel.
Take care of yourselves, and remember: even in the depths of a Norwegian winter, there is light to be found – you just need to know where to look for it, and when to turn it off.