Apple’s new OLED MacBook Pro is giving some buyers headaches, and a few of them are sending it back.

The complaints center on how the screen controls its brightness. The technique is called PWM, and it bothers a small slice of users. If you’re sensitive to it, this laptop may not be for you.

According to a report from PhoneArena , owners who are sensitive to the flicker describe headaches and dizziness. Some have returned their laptops. Even people who never had trouble with an iPhone or iPad say the MacBook Pro bothers them. The complaints so far come from individual owners, so it’s too early to say how widespread the problem is.

What PWM is, and why it matters

PWM stands for pulse-width modulation. Instead of lowering the power going to the screen, the display rapidly switches its pixels on and off. The longer they stay off, the dimmer the picture looks. Do it fast enough and almost nobody notices.…