A few years ago I bought some LED Christmas tree lights, this year I bought some traditional  incandescent lights to replace those new, fancy LED lights because they made me feel nauseous, here's why.

LEDs work on direct current, so they're only being powered half of the time, basically they are turning on and off sixty times every second, which makes them flicker. This flicker is so fast that you can't actually see them flashing, but you can react

The flickering LED lights (like strobe lights) can cause me symptoms including headaches, eyestrain, nausea, vertigo and more. If you are experiencing any of those symptoms when looking at your Christmas tree, get some new lights.

There are some tricks and even some gadgets that can help fix this problem, and they do sell "flicker free" light sets, but I found that even those can flicker, the second clip in the video below features a "flicker free" set, but as you can see, they still flicker.

By the way, the video was shot on an iPhone using the slo-mo feature, which shoots in 240 frames per second, which gives us a clear look at the flickering of these LED sets. As a comparison, if you look at the last clip in the video you can see the incandescent lights vs. the LED lights, no flickering with the top set of lights.