Verilux makes several versions of the HappyLight light therapy box. I tested the Full-Size and Compact versions. In a surprising twist, the Compact was the better performing lamp, despite being much smaller. That said, the light’s performance was still not good enough to make it useful for daily sessions, though its compact design makes it great to keep in the office or to take on trips to alleviate symptoms of jet lag.
The HappyLight Compact is one of the few lamps not advertised as a 10,000-lux light therapy box. Rather, the manufacturer suggests that longer sessions with this light have the same effect as a 10,000-lux light. This is true. You can get the same benefits from 5,000 lux as 10,000 lux – you just need to extend the time you sit in the light.
However, in my tests, this lamp produced 10,000 lux, though the reach was just 4.25 inches. At 16 inches, it had a 750-lux brightness, which is far below the recommended level. This means you have to sit very close to the lamp, even to get just 5,000 lux. Even at a foot away, the light's brightness was less than 2,000 lux. By comparison though, the Full-Size HappyLight was much worse. It had a 10,000-lux reach of just 2.5 inches and measured just 200 lux at 16 inches.
The HappyLight has a color temperature of 6,500 Kelvin. That’s 1,500 Kelvin over the recommended range set by the Center for Environmental Therapeutics (CET), an organization of experts on light therapy. Despite being free of UV radiation, the CET doesn’t recommend cooler, bluish lights over 5,000 Kelvin because they can cause aversive glare and potentially damage your retinas if you take photosensitizing medications. The full-spectrum fluorescent light bulbs don't seem particularly blue until you see them turned on next to other light therapy lamps.
This Verilux HappyLight had an interesting heat output. The lamp’s surface reached 135 degrees Fahrenheit. And while it’s certainly not the hottest lamp, it was hotter than most lights I tested. However, when I aimed it at a wall from 16 inches away, it only increased the wall’s surface temperature by 0.25 degrees. That isn’t significant enough to feel. So, while the lamp itself gets pretty warm, the heat dissipates quickly and shouldn't make you uncomfortably hot during therapy sessions.
The HappyLight Compact performed surprisingly well for its size. In fact, it was brighter than even its Full-Size counterpart. However, its light lacks the reach to provide the necessary brightness at a comfortable distance, so you have to extend your therapy sessions.