Verilux has multiple versions of its HappyLight light therapy lamp. I tested and reviewed the Full-Size and the Compact. Both are marketed as 10,000 lux lights, with the Full-Size having a larger coverage area. However, the Compact was the better performing light of the two. That said, both failed to produce impressive results. And at a color temperature of 6,500 Kelvin, the light is bluer than most of the full-spectrum lights I tested and falls outside the range recommended by the experts at the Center for Environmental Therapeutics (CET).
In my first brightness test, I measured how bright the light was 16 inches from the lamp – the recommended distance you should sit from the lamp for comfort. At that distance, the light was just 516 lux, which is not much different from a standard light bulb. In fact, the lamp's 10,000-lux reach was just 2.5 inches. To receive the full benefit of the 10,000-lux light, your face needs to practically touch the lamp. Obviously, this doesn't make for a very comfortable therapy session. That doesn't mean you can't receive the same benefits of the light at 16 inches, but you have to extend your sessions far beyond the recommended 20 to 30 minutes to do so.
Despite having a large surface area, the HappyLight Full-Size’s coverage wasn't great compared to other lamps’. The luminous intensity measured at only 200 CD, which means the light's intensity diffuses very quickly. This explains why the 10,000-lux reach was so short.
The short 10,000-lux reach is a concern, especially considering this was among the hottest lamps in my tests. After 30 minutes, the lamp’s surface was 149.3 degrees Fahrenheit, making it the hottest light I reviewed. If you sit really close to the lamp, you're going to feel that heat radiating. When I aimed the light at a wall from 16 inches away, the wall’s surface temperature increased by 1.5 degrees. By comparison, the Day-Light Sky and the Sunbox Sunlight Jr both increased the surface temperature more, though not by much, and they were far brighter.
Verilux light therapy lamps use bulbs that produce a full-spectrum light measured at a color temperature of 6,500 Kelvin. This gives it a very white, if not bluish, color. Unfortunately, the light therapy experts at the CET recommend light therapy lamps not exceed 5,000 Kelvin, as higher temperatures can cause aversive glare and potentially damage your retinas if you take photosensitizing medications.
The Verilux HappyLight Full-Size is among the larger lamps I tested, but its light performance was disappointing by comparison. Its 10,000-lux reach was only a few inches from the lamp's surface, and it got hotter than any other lamp I reviewed. In addition, it exceeds the color temperature recommendations for a light therapy lamp, which makes it potentially unsafe for some people.