Why Some LED Lights Feel Uncomfortable: Understanding PWM Flicker and Better Alternatives
5th April 2026
The truth is, most light sources flicker; very few people perceive it directly, but we still feel its effects. You may have noticed that some light bulbs emit a warm glow that somehow doesn’t feel cozy. Often, what we’re unconsciously reacting to is that subtle flicker.
It’s important to note that many people don’t consciously notice PWM flicker, and for most people, modern LED lighting poses no issues. However, for those who are sensitive, whether due to migraines, eye conditions, or individual variation, understanding these technical differences can be helpful.
The technical source of the issue is called pulse-width modulation (PWM), a method of controlling how much electricity a light source (in this case) receives at any given moment; it causes the light source to be off for a split second. Hence the flicker.
Microwave ovens use the same trick. If you’ve ever used a microwave on a setting less than 100% power, you will notice that this reduction is achieved by running the microwave at full power for a certain amount of time and then turning it off for another period of time. “Eighty percent power” doesn’t mean 80% of full power, it means full power for 80% of the time and off for 20% of the time.
PWM is an often-used default for OLED digital displays (smart device screens, computer monitors, etc), LED lights, and some incandescent bulbs.
Flicker is all around us. We usually don’t see it, because our eyes are generally good at averaging out artificial light sources, similar to how we see a rapid series of individual images as a single moving picture. But it’s still a force that causes eye strain or discomfort.