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In this article, we’ll explore how artificial lighting affects your health—and offer practical, science-backed steps to improve your home’s light environment.
The right lighting doesn’t just make your home more comfortable — it can profoundly impact your sleep, mood, hormones, and overall well-being. Once you make even small adjustments, you’ll feel the benefits immediately.
Problem 1: Blue Light Exposure at Night
Normally, as the sun sets and natural blue light from sunlight decreases, our body converts serotonin (a daytime hormone) into melatonin. But artificial blue light exposure in the evening tricks our brain into thinking it's still daytime and resets the body's master clock (also known as the suprachiasmatic nucleus or SCN). This blocks our body's natural melatonin production, which keeps us alert when we should be winding down and impacts other processes involving the pituitary gland, adrenal gland, and the rest of the hypothalamus.
This not only makes it harder to fall asleep and reduces sleep quality, particularly REM sleep, which results in daytime fatigue and elevated stress levels, but it can also have more serious effects. Research has linked nighttime blue light exposure to hormone imbalances, depression, anxiety, and increased cancer risk (Bedrosian & Nelson., 2017).
The problem of blue light exposure at night stems from the global shift to LED lighting.
Over the last two decades, LEDs have become the standard for lighting. They’re used in everything from home bulbs to phones, TVs, and monitors because they are energy efficient. However, most LED bulbs emit blue light, even if they appear warm or cool to the eye.
This is because, at their core, nearly all modern LEDs use blue light as their primary light source. Then a phosphor coating absorbs this blue light and converts it into colours. However, a substantial amount of this blue light remains, and often increases as the bulb ages.This means that even "warm" LED bulbs, like 2700K ones that resemble sunset light, still give off some blue light.
Here’s the spectrum of a typical, normal, “warm-coloured” LED.
As you can see, there is a distinct spike of blue light. This spike falls directly within the melanopic range, the portion of the spectrum that most strongly affects our circadian rhythm. So the more light within the melanopic range, the more awake we feel. This is beneficial during the day as it triggers wakefulness but it’s a problem in the evenings..
Problem 2: Flicker
Light flicker is the rapid change in brightness that occurs in artificial lights.
All artificial lights flicker to some extent, primarily because they are powered by our electricity system, which runs on alternating current (AC), but the LED itself needs to be driven by direct current (DC). This means the current continuously cycles between a positive and negative voltage, causing the lights to fluctuate rapidly in brightness.
While light flicker can be invisible to the naked eye, it can cause headaches, eyestrain, fatigue, and in extreme cases, seizures.
Traditional incandescent bulbs don't flicker because their hot filaments retain heat between current cycles, providing more stable light output compared to LEDs.
Here’s a simple experiment: take your phone, open the camera app, and switch to slow-motion mode. Then film a few LED lights (most modern lights use LEDs) for just a couple of seconds. When you replay the videos, you’ll likely notice flickering. And no, it’s not just a camera glitch — that flicker is actually happening.
LEDs typically flicker at around 120Hz (120 times per second) and most phones in slow-motion mode capture video at 240 frames per second, which is fast enough to reveal the flickering. If you want to go a step further, you can verify this using a flicker meter or a spectrometer with flicker measurement capabilities (which is what we use during our home health assessments).
Replace your evening LEDs with incandescent/halogen bulbs, or special LEDs that are designed to minimise blue light. Also replace high flicker LED bulbs with low flicker alternatives.
We personally recommend amber-tinted incandescent bulbs, but you can also opt for clear ones. These bulbs have a smooth light spectrum without a blue light spike. They also have minimal flicker because their hot filaments retain heat and continue to glow between cycles.
There are also good LEDs out there. We recommend Yuji bulbs which have a variety of different spectra for daytime or evening lighting. Healthy Home also sells bulbs that can transition between daytime and evening spectra.
And people will say that incandescents are energy-inefficient and die quickly, and there’s certainly some truth there. However, the difference isn’t nearly as stark as most people think for a couple of reasons:
So net of everything: yes, LEDs tend to last longer than incandescents. But the difference is not as stark as most people think.
Avoid artificial blue light at night as it blocks melatonin production, making it harder to fall asleep — install apps like f.lux or use Night Shift mode on your devices (or colour shift your iPhone entirely to red) to reduce blue light.
Consider investing in blue light-blocking glasses with orange lenses for evening use, which have been shown to improve sleep quality. For most people, this makes a huge — and immediate — difference in how quickly they fall asleep and how relaxed they feel.
During our home health assessments, we’ll evaluate the spectral distribution, melanopic weighting, flicker, and colour rendering of each fixture. Our analysis identifies physiologically disruptive lighting and provides targeted remediation recommendations.
We provide a full analysis of each light’s spectral distribution and key parameters, along with clear replacement recommendations and the rationale behind them. And we also work with clients to identify alternatives that match their aesthetic preferences and usage needs.
In nearly all the homes we test, we find issues with lighting, from blue light exposure in evening lighting to severe flicker.
Anecdotally, once I changed my lights, not only did I feel better and more relaxed in the evenings, but my sleep patterns totally changed. I started to naturally get much more aligned with the sun's rise, and fall and my sleep felt much deeper. It's been one of the most impactful changes I've made.
There’s a lot more to cover, and we’ll dive into it in future emails, including:
Have questions? Feel free to email us hello@universehealth.co.uk
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