Is Smart Lighting Healthy?

A Philips Hue Go smart light. Photo: Scott Lewis (CC BY 2.0)

One common objection to Bedtime Bulb is that Philips Hue* and other smart lighting systems can also get rid of sleep-disturbing blue light while giving you a lot more flexibility. I have direct experience with smart lighting, as my home has been outfitted with Hue for the last 3+ years.

In this article, I will answer the question: is smart lighting—specifically Philips Hue—actually healthy?

Pro: Color Control

One of the main selling points of the Hue system is that you can make your lights virtually any color. Note that I am referring to the most expensive Hue White and Color lineup, with bulbs costing approximately $40 each. You can see the differences between different Hue models at this link.

The ability to change to any color is appealing, although in my case, making the lights purple is only something I show off at dinner parties. On a daily basis, however, I adjust the color from a dim, warm white in the evening to a bright daylight setting in the middle of the day. This is technically just changing the color temperature (CCT) of white light, but it is still something most lighting does not let you do.

CCT scale of white light. I typically adjust my Hue lights from about 1800 K (like a candle) to 5000 K (daylight color)

In general (but not always!), a lower CCT will provide less sleep-disturbing blue/green light. CCTs around 5000 K are fine—even preferable—during the day, but they contain too much blue light for the evening.

I put 1st-gen Hue bulbs on a program changing from pure red (1000 K) at night to about 5800 K (very blue daylight) during the day. In the following video, you can watch the spectrum change over the range from 6–9 AM and 6–9 PM. Note that this is a bit extreme — you would more likely use a range from about 2000 K to 5000 K:

Watch on YouTube. Subscribe to my channel.

From the spectra in the video, it’s clear that Philips Hue can be used to control your blue light exposure throughout the day. But that’s not the end of the story.

Con: Color Performance

Watch the video again, and pay attention to the numbers in the upper-left corner. Specifically, CRI and R9. Here’s what they mean:

  • CRI (Color Rendering Index): How well colors render on a 0–100 scale. Basically, the higher the number, the better things look. Most of today’s LED lights hover around 80, but Bedtime Bulb has a CRI of 95, and traditional incandescent and halogen lighting are also in the high 90s.
  • R9: A measure of strong red rendering, up to 100. People tend to prefer lighting with a lot of red. Halogen and incandescent lighting tend to have R9 values in the 90s—this is one of the main reasons people love those light sources. Bedtime Bulb also has a very high R9 of 84. Most LED lights are really bad at red, often scoring in the single digits or even negative, causing things to look washed out.

With the exception of pure red (1000 K), Hue has a decently high CRI (85–91) for the early morning and late evening settings. But in the middle of the day, I found the number could be as low as 78, which is similar to the very cheapest LED light bulbs you can buy.

R9 was decent—but not spectacular—for the evening settings, hovering around 30–40. But in the middle of the day, it fell to just 11. A somewhat-common complaint with Hue is that people and photographs can look washed out in the daylight mode, and a low R9 is the main reason.

Knowing common cost-cutting measures for LED lighting, I have a strong feeling most other smart lights aren’t going to have better color performance than Hue. The only exception is Ketra, a smart lighting system with very good color performance, but it is extremely expensive.

Con: Flicker

Have you ever tried to take a picture with your phone and noticed black bars scrolling across the screen? Those bars mean the lighting has flicker, a rapid flashing that could promote eyestrain and headaches. Not to mention messing with your photography.

What flicker looks like on your phone camera. Watch on YouTube.

Using your phone camera is not a foolproof way to detect flicker. It could be present even though you don’t see it with the camera. But if you see black lines, your lighting definitely has flicker.

Headache-inducing flicker was a problem with early fluorescent lighting, but it was remedied in the 90s and 2000s with electronic ballasts. Unfortunately, flicker came back with LED lighting. It is a byproduct of designing for low cost, not performance.

Note that the flicker I’m referring to is not flashing you can directly see with your eyes. The frequency is usually high enough (usually 100–120 Hz) that only a trained eye could detect it. Flashing you can see with your eyes usually means the lighting electronics are malfunctioning. Even though you can’t see flicker, it could still contribute to adverse health effects.

Every Hue light I have seen has flicker. It is actually pretty hard to make a smart LED bulb that doesn’t have flicker, although not impossible. Again, Ketra is the only smart lighting manufacturer I have seen that even mentions flicker performance.

The state of California has written low-flicker requirements into law, but the rest of the world has been slow to catch up. Most manufacturers will wait as long as possible and do the minimum they can get away with when it comes to standards. Unfortunately, this comes at the expense of health and safety.

Final Thoughts

I have Philips Hue at home and still use it, mostly because it is a sunk cost and still one of the better smart lighting systems. I like the ability to control blue light exposure throughout the day and stick wireless remotes all over the house.

But that’s where the advantages end. The color performance leaves a lot to be desired, and the flicker is definitely not healthy. Beyond that, the system is expensive, and in my experience, it has proven unreliable. I have had to replace 30%(!) of my Hue bulbs after just a few years due to electronics failures. The warranty is comically short for such an expensive product.

Comparison of standard and low-blue lighting products. Bedtime Bulb has the best combination of color performance, comfort, and circadian stimulation for the evening.

While Bedtime Bulb doesn’t have all the features of Hue, it is definitely a healthier light for the evening:

  • It produces just 137 melanopic lumens, the lowest sleep-disturbing blue/green light of any low-blue or standard lighting product.
  • It has the lowest headache-inducing flicker we’ve ever seen in a bulb (<1%, even better than other “flicker-free” bulbs).
  • It has a very high CRI and R9, so everything just looks great under this light.

We’re considering expanding our healthy lighting lineup, and we’d love to hear your lighting needs and feature requests. Please send your thoughts.

In the meantime, check out Bedtime Bulb in the U.S. or Canada.


About the author

Greg Yeutter’s first word was “light.” For the last eight years, he’s been obsessed with light’s effects on health. Greg started Bedtime Bulb as a simple, affordable solution to address unhealthy blue light at night.

*Greg Yeutter, Bedtime Bulb, and SimpleBulb are in no way affiliated with Philips or Hue. This post was not endorsed by Philips. Spectral measurements of all lighting products were taken by Greg Yeutter. All opinions expressed in this article are Greg Yeutter’s own.